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Re: [PATCH v7 3/6] iio: core: Add new DMABUF interface infrastructure

by Christian König

Am 23.02.24 um 13:14 schrieb Nuno Sa: > From: Paul Cercueil <paul(a)crapouillou.net> > > Add the necessary infrastructure to the IIO core to support a new > optional DMABUF based interface. > > With this new interface, DMABUF objects (externally created) can be > attached to a IIO buffer, and subsequently used for data transfer. > > A userspace application can then use this interface to share DMABUF > objects between several interfaces, allowing it to transfer data in a > zero-copy fashion, for instance between IIO and the USB stack. > > The userspace application can also memory-map the DMABUF objects, and > access the sample data directly. The advantage of doing this vs. the > read() interface is that it avoids an extra copy of the data between the > kernel and userspace. This is particularly userful for high-speed > devices which produce several megabytes or even gigabytes of data per > second. > > As part of the interface, 3 new IOCTLs have been added: > > IIO_BUFFER_DMABUF_ATTACH_IOCTL(int fd): > Attach the DMABUF object identified by the given file descriptor to the > buffer. > > IIO_BUFFER_DMABUF_DETACH_IOCTL(int fd): > Detach the DMABUF object identified by the given file descriptor from > the buffer. Note that closing the IIO buffer's file descriptor will > automatically detach all previously attached DMABUF objects. > > IIO_BUFFER_DMABUF_ENQUEUE_IOCTL(struct iio_dmabuf *): > Request a data transfer to/from the given DMABUF object. Its file > descriptor, as well as the transfer size and flags are provided in the > "iio_dmabuf" structure. > > These three IOCTLs have to be performed on the IIO buffer's file > descriptor, obtained using the IIO_BUFFER_GET_FD_IOCTL() ioctl. A few nit picks and one bug below, apart from that looks good to me. > > Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> > Signed-off-by: Nuno Sa <nuno.sa(a)analog.com> > --- > drivers/iio/industrialio-buffer.c | 462 ++++++++++++++++++++++++++++++++++++++ > include/linux/iio/buffer_impl.h | 33 +++ > include/uapi/linux/iio/buffer.h | 22 ++ > 3 files changed, 517 insertions(+) > > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c > index b581a7e80566..0e63a09fa90a 100644 > --- a/drivers/iio/industrialio-buffer.c > +++ b/drivers/iio/industrialio-buffer.c > @@ -9,14 +9,19 @@ > * - Better memory allocation techniques? > * - Alternative access techniques? > */ > +#include <linux/atomic.h> > #include <linux/anon_inodes.h> > #include <linux/kernel.h> > #include <linux/export.h> > #include <linux/device.h> > +#include <linux/dma-buf.h> > +#include <linux/dma-fence.h> > +#include <linux/dma-resv.h> > #include <linux/file.h> > #include <linux/fs.h> > #include <linux/cdev.h> > #include <linux/slab.h> > +#include <linux/mm.h> > #include <linux/poll.h> > #include <linux/sched/signal.h> > > @@ -28,6 +33,32 @@ > #include <linux/iio/buffer.h> > #include <linux/iio/buffer_impl.h> > > +#define DMABUF_ENQUEUE_TIMEOUT_MS 5000 > + > +struct iio_dma_fence; > + > +struct iio_dmabuf_priv { > + struct list_head entry; > + struct kref ref; > + > + struct iio_buffer *buffer; > + struct iio_dma_buffer_block *block; > + > + u64 context; > + spinlock_t lock; > + > + struct dma_buf_attachment *attach; > + struct sg_table *sgt; > + enum dma_data_direction dir; > + atomic_t seqno; > +}; > + > +struct iio_dma_fence { > + struct dma_fence base; > + struct iio_dmabuf_priv *priv; > + struct work_struct work; > +}; > + > static const char * const iio_endian_prefix[] = { > [IIO_BE] = "be", > [IIO_LE] = "le", > @@ -332,6 +363,8 @@ void iio_buffer_init(struct iio_buffer *buffer) > { > INIT_LIST_HEAD(&buffer->demux_list); > INIT_LIST_HEAD(&buffer->buffer_list); > + INIT_LIST_HEAD(&buffer->dmabufs); > + mutex_init(&buffer->dmabufs_mutex); > init_waitqueue_head(&buffer->pollq); > kref_init(&buffer->ref); > if (!buffer->watermark) > @@ -1519,14 +1552,62 @@ static void iio_buffer_unregister_legacy_sysfs_groups(struct iio_dev *indio_dev) > kfree(iio_dev_opaque->legacy_scan_el_group.attrs); > } > > +static void iio_buffer_dmabuf_release(struct kref *ref) > +{ > + struct iio_dmabuf_priv *priv = container_of(ref, struct iio_dmabuf_priv, ref); > + struct dma_buf_attachment *attach = priv->attach; > + struct iio_buffer *buffer = priv->buffer; > + struct dma_buf *dmabuf = attach->dmabuf; > + > + dma_resv_lock(dmabuf->resv, NULL); > + dma_buf_unmap_attachment(attach, priv->sgt, priv->dir); > + dma_resv_unlock(dmabuf->resv); > + > + buffer->access->detach_dmabuf(buffer, priv->block); > + > + dma_buf_detach(attach->dmabuf, attach); > + dma_buf_put(dmabuf); > + kfree(priv); > +} > + > +void iio_buffer_dmabuf_get(struct dma_buf_attachment *attach) > +{ > + struct iio_dmabuf_priv *priv = attach->importer_priv; > + > + kref_get(&priv->ref); > +} > +EXPORT_SYMBOL_GPL(iio_buffer_dmabuf_get); > + > +void iio_buffer_dmabuf_put(struct dma_buf_attachment *attach) > +{ > + struct iio_dmabuf_priv *priv = attach->importer_priv; > + > + kref_put(&priv->ref, iio_buffer_dmabuf_release); > +} > +EXPORT_SYMBOL_GPL(iio_buffer_dmabuf_put); > + > static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) > { > struct iio_dev_buffer_pair *ib = filep->private_data; > struct iio_dev *indio_dev = ib->indio_dev; > struct iio_buffer *buffer = ib->buffer; > + struct iio_dmabuf_priv *priv, *tmp; > > wake_up(&buffer->pollq); > > + mutex_lock(&buffer->dmabufs_mutex); > + > + /* Close all attached DMABUFs */ > + list_for_each_entry_safe(priv, tmp, &buffer->dmabufs, entry) { > + list_del_init(&priv->entry); > + iio_buffer_dmabuf_put(priv->attach); > + } > + > + if (!list_empty(&buffer->dmabufs)) > + dev_warn(&indio_dev->dev, "Buffer FD closed with active transfers\n"); That check here smells fishy. Either the list_for_each_entry_safe() above has removed all entries and then it can never happen or the buffer list is not always properly protected by the mutex. Do you really need that? If yes then please justify. BTW: When the transfers are async it's perfectly possible that there are active transfers on close (when the application is just killed for example). > + > + mutex_unlock(&buffer->dmabufs_mutex); > + > kfree(ib); > clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); > iio_device_put(indio_dev); > @@ -1534,11 +1615,391 @@ static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) > return 0; > } > > +static int iio_dma_resv_lock(struct dma_buf *dmabuf, bool nonblock) > +{ > + if (!nonblock) > + return dma_resv_lock_interruptible(dmabuf->resv, NULL); > + > + if (!dma_resv_trylock(dmabuf->resv)) > + return -EBUSY; > + > + return 0; > +} > + > +static struct dma_buf_attachment * > +iio_buffer_find_attachment(struct iio_dev_buffer_pair *ib, > + struct dma_buf *dmabuf, bool nonblock) > +{ > + struct device *dev = ib->indio_dev->dev.parent; > + struct iio_buffer *buffer = ib->buffer; > + struct dma_buf_attachment *attach = NULL; > + struct iio_dmabuf_priv *priv; > + > + mutex_lock(&buffer->dmabufs_mutex); > + > + list_for_each_entry(priv, &buffer->dmabufs, entry) { > + if (priv->attach->dev == dev > + && priv->attach->dmabuf == dmabuf) { > + attach = priv->attach; > + break; > + } > + } > + > + if (attach) > + iio_buffer_dmabuf_get(attach); > + > + mutex_unlock(&buffer->dmabufs_mutex); > + > + return attach ?: ERR_PTR(-EPERM); > +} > + > +static int iio_buffer_attach_dmabuf(struct iio_dev_buffer_pair *ib, > + int __user *user_fd, bool nonblock) > +{ > + struct iio_dev *indio_dev = ib->indio_dev; > + struct iio_buffer *buffer = ib->buffer; > + struct dma_buf_attachment *attach; > + struct iio_dmabuf_priv *priv; > + struct dma_buf *dmabuf; > + int err, fd; > + > + if (!buffer->access->attach_dmabuf > + || !buffer->access->detach_dmabuf > + || !buffer->access->enqueue_dmabuf) > + return -EPERM; > + > + if (copy_from_user(&fd, user_fd, sizeof(fd))) > + return -EFAULT; > + > + priv = kzalloc(sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + > + spin_lock_init(&priv->lock); > + priv->context = dma_fence_context_alloc(1); > + > + dmabuf = dma_buf_get(fd); > + if (IS_ERR(dmabuf)) { > + err = PTR_ERR(dmabuf); > + goto err_free_priv; > + } > + > + attach = dma_buf_attach(dmabuf, indio_dev->dev.parent); > + if (IS_ERR(attach)) { > + err = PTR_ERR(attach); > + goto err_dmabuf_put; > + } > + > + err = iio_dma_resv_lock(dmabuf, nonblock); > + if (err) > + goto err_dmabuf_detach; > + > + priv->dir = buffer->direction == IIO_BUFFER_DIRECTION_IN > + ? DMA_FROM_DEVICE : DMA_TO_DEVICE; > + > + priv->sgt = dma_buf_map_attachment(attach, priv->dir); > + if (IS_ERR(priv->sgt)) { > + err = PTR_ERR(priv->sgt); > + dev_err(&indio_dev->dev, "Unable to map attachment: %d\n", err); > + goto err_resv_unlock; > + } > + > + kref_init(&priv->ref); > + priv->buffer = buffer; > + priv->attach = attach; > + attach->importer_priv = priv; > + > + priv->block = buffer->access->attach_dmabuf(buffer, attach); > + if (IS_ERR(priv->block)) { > + err = PTR_ERR(priv->block); > + goto err_dmabuf_unmap_attachment; > + } > + > + dma_resv_unlock(dmabuf->resv); > + > + mutex_lock(&buffer->dmabufs_mutex); > + list_add(&priv->entry, &buffer->dmabufs); > + mutex_unlock(&buffer->dmabufs_mutex); Is it valid to attach the same dma_buf multiple times? If not that code here should probably check that. > + > + return 0; > + > +err_dmabuf_unmap_attachment: > + dma_buf_unmap_attachment(attach, priv->sgt, priv->dir); > +err_resv_unlock: > + dma_resv_unlock(dmabuf->resv); > +err_dmabuf_detach: > + dma_buf_detach(dmabuf, attach); > +err_dmabuf_put: > + dma_buf_put(dmabuf); > +err_free_priv: > + kfree(priv); > + > + return err; > +} > + > +static int iio_buffer_detach_dmabuf(struct iio_dev_buffer_pair *ib, > + int *user_req, bool nonblock) > +{ > + struct iio_buffer *buffer = ib->buffer; > + struct iio_dev *indio_dev = ib->indio_dev; > + struct iio_dmabuf_priv *priv; > + struct dma_buf *dmabuf; > + int dmabuf_fd, ret = -EPERM; ENOENT is more common to use when something can't be found I think, but perfectly up to you what you prefer. > + > + if (copy_from_user(&dmabuf_fd, user_req, sizeof(dmabuf_fd))) > + return -EFAULT; > + > + dmabuf = dma_buf_get(dmabuf_fd); > + if (IS_ERR(dmabuf)) > + return PTR_ERR(dmabuf); > + > + mutex_lock(&buffer->dmabufs_mutex); > + > + list_for_each_entry(priv, &buffer->dmabufs, entry) { > + if (priv->attach->dev == indio_dev->dev.parent > + && priv->attach->dmabuf == dmabuf) { > + list_del(&priv->entry); > + > + /* Unref the reference from iio_buffer_attach_dmabuf() */ > + iio_buffer_dmabuf_put(priv->attach); > + ret = 0; > + break; > + } > + } > + > + mutex_unlock(&buffer->dmabufs_mutex); > + dma_buf_put(dmabuf); > + > + return ret; > +} > + > +static const char * > +iio_buffer_dma_fence_get_driver_name(struct dma_fence *fence) > +{ > + return "iio"; > +} > + > +static void iio_buffer_dma_fence_release(struct dma_fence *fence) > +{ > + struct iio_dma_fence *iio_fence = > + container_of(fence, struct iio_dma_fence, base); > + > + kfree(iio_fence); > +} > + > +static const struct dma_fence_ops iio_buffer_dma_fence_ops = { > + .get_driver_name = iio_buffer_dma_fence_get_driver_name, > + .get_timeline_name = iio_buffer_dma_fence_get_driver_name, > + .release = iio_buffer_dma_fence_release, > +}; > + > +static int iio_buffer_enqueue_dmabuf(struct iio_dev_buffer_pair *ib, > + struct iio_dmabuf __user *iio_dmabuf_req, > + bool nonblock) > +{ > + struct iio_buffer *buffer = ib->buffer; > + struct iio_dmabuf iio_dmabuf; > + struct dma_buf_attachment *attach; > + struct iio_dmabuf_priv *priv; > + struct iio_dma_fence *fence; > + struct dma_buf *dmabuf; > + unsigned long timeout; > + bool cookie, cyclic, dma_to_ram; > + long retl; > + u32 seqno; > + int ret; > + > + if (copy_from_user(&iio_dmabuf, iio_dmabuf_req, sizeof(iio_dmabuf))) > + return -EFAULT; > + > + if (iio_dmabuf.flags & ~IIO_BUFFER_DMABUF_SUPPORTED_FLAGS) > + return -EINVAL; > + > + cyclic = iio_dmabuf.flags & IIO_BUFFER_DMABUF_CYCLIC; > + > + /* Cyclic flag is only supported on output buffers */ > + if (cyclic && buffer->direction != IIO_BUFFER_DIRECTION_OUT) > + return -EINVAL; > + > + dmabuf = dma_buf_get(iio_dmabuf.fd); > + if (IS_ERR(dmabuf)) > + return PTR_ERR(dmabuf); > + > + if (!iio_dmabuf.bytes_used || iio_dmabuf.bytes_used > dmabuf->size) { > + ret = -EINVAL; > + goto err_dmabuf_put; > + } > + > + attach = iio_buffer_find_attachment(ib, dmabuf, nonblock); > + if (IS_ERR(attach)) { > + ret = PTR_ERR(attach); > + goto err_dmabuf_put; > + } > + > + priv = attach->importer_priv; > + > + fence = kmalloc(sizeof(*fence), GFP_KERNEL); > + if (!fence) { > + ret = -ENOMEM; > + goto err_attachment_put; > + } > + > + fence->priv = priv; > + > + seqno = atomic_add_return(1, &priv->seqno); > + > + /* > + * The transfers are guaranteed to be processed in the order they are > + * enqueued, so we can use a simple incrementing sequence number for > + * the dma_fence. > + */ > + dma_fence_init(&fence->base, &iio_buffer_dma_fence_ops, > + &priv->lock, priv->context, seqno); > + > + ret = iio_dma_resv_lock(dmabuf, nonblock); > + if (ret) > + goto err_fence_put; > + > + timeout = nonblock ? 0 : msecs_to_jiffies(DMABUF_ENQUEUE_TIMEOUT_MS); > + > + /* Make sure we don't have writers */ > + retl = dma_resv_wait_timeout(dmabuf->resv, DMA_RESV_USAGE_WRITE, > + true, timeout); > + if (retl == 0) > + retl = -EBUSY; > + if (retl < 0) { > + ret = (int)retl; > + goto err_resv_unlock; > + } > + > + dma_to_ram = buffer->direction == IIO_BUFFER_DIRECTION_IN; > + > + if (dma_to_ram) { > + /* > + * If we're writing to the DMABUF, make sure we don't have > + * readers > + */ > + retl = dma_resv_wait_timeout(dmabuf->resv, > + DMA_RESV_USAGE_READ, true, > + timeout); > + if (retl == 0) > + retl = -EBUSY; > + if (retl < 0) { > + ret = (int)retl; > + goto err_resv_unlock; > + } > + } > + > + if (buffer->access->lock_queue) > + buffer->access->lock_queue(buffer); > + > + ret = dma_resv_reserve_fences(dmabuf->resv, 1); > + if (ret) > + goto err_queue_unlock; > + > + dma_resv_add_fence(dmabuf->resv, &fence->base, > + dma_resv_usage_rw(dma_to_ram)); That is incorrect use of the function dma_resv_usage_rw(). That function is for retrieving fences and not adding them. See the function implementation and comments, when you use it like this you get exactly what you don't want. Regards, Christian. > + dma_resv_unlock(dmabuf->resv); > + > + cookie = dma_fence_begin_signalling(); > + > + ret = buffer->access->enqueue_dmabuf(buffer, priv->block, &fence->base, > + priv->sgt, iio_dmabuf.bytes_used, > + cyclic); > + if (ret) { > + /* > + * DMABUF enqueue failed, but we already added the fence. > + * Signal the error through the fence completion mechanism. > + */ > + iio_buffer_signal_dmabuf_done(&fence->base, ret); > + } > + > + if (buffer->access->unlock_queue) > + buffer->access->unlock_queue(buffer); > + > + dma_fence_end_signalling(cookie); > + dma_buf_put(dmabuf); > + > + return ret; > + > +err_queue_unlock: > + if (buffer->access->unlock_queue) > + buffer->access->unlock_queue(buffer); > +err_resv_unlock: > + dma_resv_unlock(dmabuf->resv); > +err_fence_put: > + dma_fence_put(&fence->base); > +err_attachment_put: > + iio_buffer_dmabuf_put(attach); > +err_dmabuf_put: > + dma_buf_put(dmabuf); > + > + return ret; > +} > + > +static void iio_buffer_cleanup(struct work_struct *work) > +{ > + struct iio_dma_fence *fence = > + container_of(work, struct iio_dma_fence, work); > + struct iio_dmabuf_priv *priv = fence->priv; > + struct dma_buf_attachment *attach = priv->attach; > + > + dma_fence_put(&fence->base); > + iio_buffer_dmabuf_put(attach); > +} > + > +void iio_buffer_signal_dmabuf_done(struct dma_fence *fence, int ret) > +{ > + struct iio_dma_fence *iio_fence = > + container_of(fence, struct iio_dma_fence, base); > + bool cookie = dma_fence_begin_signalling(); > + > + /* > + * Get a reference to the fence, so that it's not freed as soon as > + * it's signaled. > + */ > + dma_fence_get(fence); > + > + fence->error = ret; > + dma_fence_signal(fence); > + dma_fence_end_signalling(cookie); > + > + /* > + * The fence will be unref'd in iio_buffer_cleanup. > + * It can't be done here, as the unref functions might try to lock the > + * resv object, which can deadlock. > + */ > + INIT_WORK(&iio_fence->work, iio_buffer_cleanup); > + schedule_work(&iio_fence->work); > +} > +EXPORT_SYMBOL_GPL(iio_buffer_signal_dmabuf_done); > + > +static long iio_buffer_chrdev_ioctl(struct file *filp, > + unsigned int cmd, unsigned long arg) > +{ > + struct iio_dev_buffer_pair *ib = filp->private_data; > + void __user *_arg = (void __user *)arg; > + bool nonblock = filp->f_flags & O_NONBLOCK; > + > + switch (cmd) { > + case IIO_BUFFER_DMABUF_ATTACH_IOCTL: > + return iio_buffer_attach_dmabuf(ib, _arg, nonblock); > + case IIO_BUFFER_DMABUF_DETACH_IOCTL: > + return iio_buffer_detach_dmabuf(ib, _arg, nonblock); > + case IIO_BUFFER_DMABUF_ENQUEUE_IOCTL: > + return iio_buffer_enqueue_dmabuf(ib, _arg, nonblock); > + default: > + return -EINVAL; > + } > +} > + > static const struct file_operations iio_buffer_chrdev_fileops = { > .owner = THIS_MODULE, > .llseek = noop_llseek, > .read = iio_buffer_read, > .write = iio_buffer_write, > + .unlocked_ioctl = iio_buffer_chrdev_ioctl, > + .compat_ioctl = compat_ptr_ioctl, > .poll = iio_buffer_poll, > .release = iio_buffer_chrdev_release, > }; > @@ -1953,6 +2414,7 @@ static void iio_buffer_release(struct kref *ref) > { > struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref); > > + mutex_destroy(&buffer->dmabufs_mutex); > buffer->access->release(buffer); > } > > diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h > index 89c3fd7c29ca..f4b1147291e5 100644 > --- a/include/linux/iio/buffer_impl.h > +++ b/include/linux/iio/buffer_impl.h > @@ -9,8 +9,12 @@ > #include <uapi/linux/iio/buffer.h> > #include <linux/iio/buffer.h> > > +struct dma_buf_attachment; > +struct dma_fence; > struct iio_dev; > +struct iio_dma_buffer_block; > struct iio_buffer; > +struct sg_table; > > /** > * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be > @@ -39,6 +43,13 @@ struct iio_buffer; > * device stops sampling. Calles are balanced with @enable. > * @release: called when the last reference to the buffer is dropped, > * should free all resources allocated by the buffer. > + * @attach_dmabuf: called from userspace via ioctl to attach one external > + * DMABUF. > + * @detach_dmabuf: called from userspace via ioctl to detach one previously > + * attached DMABUF. > + * @enqueue_dmabuf: called from userspace via ioctl to queue this DMABUF > + * object to this buffer. Requires a valid DMABUF fd, that > + * was previouly attached to this buffer. > * @modes: Supported operating modes by this buffer type > * @flags: A bitmask combination of INDIO_BUFFER_FLAG_* > * > @@ -68,6 +79,17 @@ struct iio_buffer_access_funcs { > > void (*release)(struct iio_buffer *buffer); > > + struct iio_dma_buffer_block * (*attach_dmabuf)(struct iio_buffer *buffer, > + struct dma_buf_attachment *attach); > + void (*detach_dmabuf)(struct iio_buffer *buffer, > + struct iio_dma_buffer_block *block); > + int (*enqueue_dmabuf)(struct iio_buffer *buffer, > + struct iio_dma_buffer_block *block, > + struct dma_fence *fence, struct sg_table *sgt, > + size_t size, bool cyclic); > + void (*lock_queue)(struct iio_buffer *buffer); > + void (*unlock_queue)(struct iio_buffer *buffer); > + > unsigned int modes; > unsigned int flags; > }; > @@ -136,6 +158,12 @@ struct iio_buffer { > > /* @ref: Reference count of the buffer. */ > struct kref ref; > + > + /* @dmabufs: List of DMABUF attachments */ > + struct list_head dmabufs; /* P: dmabufs_mutex */ > + > + /* @dmabufs_mutex: Protects dmabufs */ > + struct mutex dmabufs_mutex; > }; > > /** > @@ -156,9 +184,14 @@ int iio_update_buffers(struct iio_dev *indio_dev, > **/ > void iio_buffer_init(struct iio_buffer *buffer); > > +void iio_buffer_dmabuf_get(struct dma_buf_attachment *attach); > +void iio_buffer_dmabuf_put(struct dma_buf_attachment *attach); > + > struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer); > void iio_buffer_put(struct iio_buffer *buffer); > > +void iio_buffer_signal_dmabuf_done(struct dma_fence *fence, int ret); > + > #else /* CONFIG_IIO_BUFFER */ > > static inline void iio_buffer_get(struct iio_buffer *buffer) {} > diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h > index 13939032b3f6..c666aa95e532 100644 > --- a/include/uapi/linux/iio/buffer.h > +++ b/include/uapi/linux/iio/buffer.h > @@ -5,6 +5,28 @@ > #ifndef _UAPI_IIO_BUFFER_H_ > #define _UAPI_IIO_BUFFER_H_ > > +#include <linux/types.h> > + > +/* Flags for iio_dmabuf.flags */ > +#define IIO_BUFFER_DMABUF_CYCLIC (1 << 0) > +#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000001 > + > +/** > + * struct iio_dmabuf - Descriptor for a single IIO DMABUF object > + * @fd: file descriptor of the DMABUF object > + * @flags: one or more IIO_BUFFER_DMABUF_* flags > + * @bytes_used: number of bytes used in this DMABUF for the data transfer. > + * Should generally be set to the DMABUF's size. > + */ > +struct iio_dmabuf { > + __u32 fd; > + __u32 flags; > + __u64 bytes_used; > +}; > + > #define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0x91, int) > +#define IIO_BUFFER_DMABUF_ATTACH_IOCTL _IOW('i', 0x92, int) > +#define IIO_BUFFER_DMABUF_DETACH_IOCTL _IOW('i', 0x93, int) > +#define IIO_BUFFER_DMABUF_ENQUEUE_IOCTL _IOW('i', 0x94, struct iio_dmabuf) > > #endif /* _UAPI_IIO_BUFFER_H_ */ >

1 year, 6 months

Re: [PATCH v7 1/6] dmaengine: Add API function dmaengine_prep_peripheral_dma_vec()

by Nuno Sá

On Fri, 2024-02-23 at 13:13 +0100, Nuno Sa wrote: > From: Paul Cercueil <paul(a)crapouillou.net> > > This function can be used to initiate a scatter-gather DMA transfer, > where the address and size of each segment is located in one entry of > the dma_vec array. > > The major difference with dmaengine_prep_slave_sg() is that it supports > specifying the lengths of each DMA transfer; as trying to override the > length of the transfer with dmaengine_prep_slave_sg() is a very tedious > process. The introduction of a new API function is also justified by the > fact that scatterlists are on their way out. > > Note that dmaengine_prep_interleaved_dma() is not helpful either in that > case, as it assumes that the address of each segment will be higher than > the one of the previous segment, which we just cannot guarantee in case > of a scatter-gather transfer. > > Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> > Signed-off-by: Nuno Sa <nuno.sa(a)analog.com> > --- Hi Vinod, Is this already good for you? I do not want to be pushy but we're trying to see if we can have this in the 6.9 cycle and Jonathan definitely wants an ack from you before merging this in his tree. I've more or less till Wednesday so that's why I'm asking already today so I still have time to re-spin if you want some changes. - Nuno Sá

1 year, 6 months

Re: [PATCH v7 0/6] iio: new DMABUF based API

by Jonathan Cameron

On Fri, 23 Feb 2024 13:13:58 +0100 Nuno Sa <nuno.sa(a)analog.com> wrote: > Hi Jonathan, likely you're wondering why I'm sending v7. Well, to be > honest, we're hoping to get this merged this for the 6.9 merge window. > Main reason is because the USB part is already in (so it would be nice > to get the whole thing in). Moreover, the changes asked in v6 were simple > (even though I'm not quite sure in one of them) and Paul has no access to > it's laptop so he can't send v7 himself. So he kind of said/asked for me to do it. So, we are cutting this very fine. If Linus hints strongly at an rc8 maybe we can sneak this in. However, I need an Ack from Vinod for the dma engine changes first. Also I'd love a final 'looks ok' comment from DMABUF folk (Ack even better!) Seems that the other side got resolved in the USB gadget, but last we heard form Daniel and Christian looks to have been back on v5. I'd like them to confirm they are fine with the changes made as a result. I've been happy with the IIO parts for a few versions now but my ability to review the DMABUF and DMA engine bits is limited. A realistic path to get this in is rc8 is happening, is all Acks in place by Wednesday, I get apply it and hits Linux-next Thursday, Pull request to Greg on Saturday and Greg is feeling particularly generous to take one on the day he normally closes his trees. Whilst I'll cross my fingers, looks like 6.10 material to me :( I'd missed the progress on the USB side so wasn't paying enough attention. Sorry! Jonathan > > v6: > * https://lore.kernel.org/linux-iio/20240129170201.133785-1-paul@crapouillou.… > > v7: > - Patch 1 > * Renamed *device_prep_slave_dma_vec() -> device_prep_peripheral_dma_vec(); > * Added a new flag parameter to the function as agreed between Paul > and Vinod. I renamed the first parameter to prep_flags as it's supposed to > be used (I think) with enum dma_ctrl_flags. I'm not really sure how that API > can grow but I was thinking in just having a bool cyclic parameter (as the > first intention of the flags is to support cyclic transfers) but ended up > "respecting" the previously agreed approach. > - Patch 2 > * Adapted patch for the changes made in patch 1. > - Patch 5 > * Adapted patch for the changes made in patch 1. > > Patchset based on next-20240223. > > --- > Paul Cercueil (6): > dmaengine: Add API function dmaengine_prep_peripheral_dma_vec() > dmaengine: dma-axi-dmac: Implement device_prep_peripheral_dma_vec > iio: core: Add new DMABUF interface infrastructure > iio: buffer-dma: Enable support for DMABUFs > iio: buffer-dmaengine: Support new DMABUF based userspace API > Documentation: iio: Document high-speed DMABUF based API > > Documentation/iio/dmabuf_api.rst | 54 +++ > Documentation/iio/index.rst | 2 + > drivers/dma/dma-axi-dmac.c | 40 ++ > drivers/iio/buffer/industrialio-buffer-dma.c | 181 +++++++- > drivers/iio/buffer/industrialio-buffer-dmaengine.c | 59 ++- > drivers/iio/industrialio-buffer.c | 462 +++++++++++++++++++++ > include/linux/dmaengine.h | 27 ++ > include/linux/iio/buffer-dma.h | 31 ++ > include/linux/iio/buffer_impl.h | 33 ++ > include/uapi/linux/iio/buffer.h | 22 + > 10 files changed, 894 insertions(+), 17 deletions(-) > --- > base-commit: 33e1d31873f87d119e5120b88cd350efa68ef276 > change-id: 20240223-iio-dmabuf-5ee0530195ca > -- > > Thanks! > - Nuno Sá >

1 year, 6 months

Re: [PATCH v2 2/2] net: ethernet: ti: am65-cpsw: Add minimal XDP support

by Andrew Lunn

On Fri, Mar 01, 2024 at 04:02:53PM +0100, Julien Panis wrote: > This patch adds XDP (eXpress Data Path) support to TI AM65 CPSW > Ethernet driver. The following features are implemented: > - NETDEV_XDP_ACT_BASIC (XDP_PASS, XDP_TX, XDP_DROP, XDP_ABORTED) > - NETDEV_XDP_ACT_REDIRECT (XDP_REDIRECT) > - NETDEV_XDP_ACT_NDO_XMIT (ndo_xdp_xmit callback) > > The page pool memory model is used to get better performance. Do you have any benchmark numbers? It should help with none XDP traffic as well. So maybe iperf numbers before and after? Andrew

1 year, 6 months

Re: (subset) [PATCH 13/18] mfd: mt6397-core: register mt6357 sound codec

by Lee Jones

On Mon, 26 Feb 2024 15:01:51 +0100, amergnat(a)baylibre.com wrote: > Add MT6357 codec entry in the MFD driver. > > Applied, thanks! [13/18] mfd: mt6397-core: register mt6357 sound codec commit: 79d98102a31ab777b4a6632d799ab2bc63654cf8 -- Lee Jones [李琼斯]

1 year, 6 months

[PATCH v2 0/3] Add GAMMA 12-bit LUT support for MT8188

by Jason-JH.Lin

From: Jason-jh Lin <jason-jh.lin(a)mediatek.corp-partner.google.com> Since MT8195 supports GAMMA 12-bit LUT after the landing of [1] series, we can now add support for MT8188. [1] MediaTek DDP GAMMA - 12-bit LUT support - https://patchwork.kernel.org/project/linux-mediatek/list/?series=792516 Change in v2: 1. Keep MT8195 compatible in the group of MT8183. 2. Move MT8195 compatible group to the end of items list. Jason-JH.Lin (3): dt-bindings: display: mediatek: gamma: Change MT8195 to single enum group dt-bindings: display: mediatek: gamma: Add support for MT8188 drm/mediatek: Add gamma support for MT8195 .../devicetree/bindings/display/mediatek/mediatek,gamma.yaml | 5 +++++ drivers/gpu/drm/mediatek/mtk_drm_drv.c | 2 ++ 2 files changed, 7 insertions(+) -- 2.18.0

1 year, 6 months

Re: [PATCH] net: ethernet: ti: am65-cpsw: Add minimal XDP support

by Andrew Lunn

On Thu, Feb 29, 2024 at 05:19:44PM +0100, Julien Panis wrote: > On 2/27/24 00:18, Andrew Lunn wrote: > > > +static struct sk_buff *am65_cpsw_alloc_skb(struct net_device *ndev, unsigned int len) > > > +{ > > > + struct page *page; > > > + struct sk_buff *skb; > > > + > > > + page = dev_alloc_pages(0); > > You are likely to get better performance if you use the page_pool. > > > > When FEC added XDP support, the first set of changes was to make use > > of page_pool. That improved the drivers performance. Then XDP was > > added on top. Maybe you can follow that pattern. > > > > Andrew > > Hello Andrew, > > Thanks for this suggestion. I've been working on it over the last days. > I encountered issues and I begin to wonder if that's a good option for > this driver. Let me explain... I'm not a page pool expert, so hopefully those that are will jump in and help. > This device has 3 ports: > - Port0 is the host port (internal to the subsystem and referred as CPPI > in the driver). > - Port1 and 2 are the external ethernet ports. > Each port's RX FIFO has 1 queue. > > As mentioned in page_pool documentation: > https://docs.kernel.org/networking/page_pool.html > "The number of pools created MUST match the number of hardware > queues unless hardware restrictions make that impossible. This would > otherwise beat the purpose of page pool, which is allocate pages fast > from cache without locking." My guess is, this last bit is the important part. Locking. Do ports 1 and port 2 rx and tx run in parallel on different CPUs? Hence do you need locking? > So, for this driver I should use 2 page pools (for port1 and 2) if possible. Maybe, maybe not. It is not really the number of front panel interface which matters here. It is the number of entities which need buffers. > But, if I I replace any alloc_skb() with page_pool_alloc() in the original > driver, I will have to create only 1 page_pool. > This is visible in am65_cpsw_nuss_common_open(), which starts with: > "if (common->usage_count) return 0;" to ensure that subsequent code > will be executed only once even if the 2 interfaces are ndo_open'd. > IOW, skbs will be allocated for only 1 RX channel. I checked that behavior, > and that's the way it works. > This is because the host port (CPPI) has only 1 RX queue. This single > queue is used to get all the packets, from both Ports and 2 (port ID is > stored in each descriptor). So you have one entity which needs buffers. CPPI. It seems like Port1 and Port2 do not need buffers? So to me, you need one page pool. > So, because of this constraint, I ended up working on the "single > page pool" option. > > Questions: > 1) Is the behavior described above usual for ethernet switch devices ? This might be the first time page pool has been used by a switch? I would check the melanox and sparx5 driver and see if they use page pool. > 2) Given that I can't use a page pool for each HW queue, is it worth > using the page pool memory model ? > 3) Currently I use 2 xdp_rxq (one for port1 and another one for port2). > If an XDP program is attached to port1, my page pool dma parameter > will need to be DMA_BIDIRECTIONAL (because of XDP_TX). As a result, > even if there is no XDP program attached to port2, the setting for page > pool will need to be DMA_BIDIRECTIONAL instead of DMA_FROM_DEVICE. > In such situation, isn't it a problem for port2 ? > 4) Because of 1) and 2), will page pool performance really be better for > this driver ? You probably need to explain the TX architecture a bit. How are packets passed to the hardware? Is it again via a single CPPI entity? Or are there two entities? DMA_BIDIRECTIONAL and DMA_FROM_DEVICE is about cache flushing and invalidation. Before you pass a buffer to the hardware for it to receive into, you need to invalidate the cache. That means when the hardware gives the buffer back with a packet in it, there is a cache miss and it fetches the new data from memory. If that packet gets turned into an XDP_TX, you need to flush the cache to force any changes out of the cache and into memory. The DMA from memory then gets the up to date packet contents. My guess would be, always using DMA_BIDIRECTIONAL is fine, so long as your cache operations are correct. Turn on DMA_API_DEBUG and make sure it is happy. Andrew

1 year, 6 months

[PATCH 0/3] Add GAMMA 12-bit LUT support for MT8188

by Jason-JH.Lin

From: Jason-jh Lin <jason-jh.lin(a)mediatek.corp-partner.google.com> Since MT8195 supports GAMMA 12-bit LUT after the landing of [1] series, we can now add support for MT8188. [1] MediaTek DDP GAMMA - 12-bit LUT support - https://patchwork.kernel.org/project/linux-mediatek/list/?series=792516 Jason-JH.Lin (3): dt-bindings: display: mediatek: gamma: Change MT8195 to single enum group dt-bindings: display: mediatek: gamma: Add support for MT8188 drm/mediatek: Add gamma support for MT8195 .../bindings/display/mediatek/mediatek,gamma.yaml | 6 +++++- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 2 ++ 2 files changed, 7 insertions(+), 1 deletion(-) -- 2.18.0

1 year, 6 months

Re: ECC memory semantics for heaps

by John Stultz

On Wed, Feb 28, 2024 at 7:24 AM Maxime Ripard <mripard(a)redhat.com> wrote: > > I'm currently working on a platform that seems to have togglable RAM ECC > support. Enabling ECC reduces the memory capacity and memory bandwidth, > so while it's a good idea to protect most of the system, it's not worth > it for things like framebuffers that won't really be affected by a > bitflip. > > It's currently setup by enabling ECC on the entire memory, and then > having a region of memory where ECC is disabled and where we're supposed > to allocate from for allocations that don't need it. > > My first thought to support this was to create a reserved memory region > for the !ECC memory, and to create a heap to allocate buffers from that > region. That would leave the system protected by ECC, while enabling > userspace to be nicer to the system by allocating buffers from the !ECC > region if it doesn't need it. > > However, this creates basically a new combination compared to the one we > already have (ie, physically contiguous vs virtually contiguous), and we > probably would want to throw in cacheable vs non-cacheable too. > > If we had to provide new heaps for each variation, we would have 8 heaps > (and 6 new ones), which could be fine I guess but would still increase > quite a lot the number of heaps we have so far. > > Is it something that would be a problem? If it is, do you see another > way to support those kind of allocations (like providing hints through > the ioctl maybe?)? So, the dma-buf heaps interface uses chardevs so that we can have a lot of flexibility in the types of heaps (and don't have the risk of bitmask exhaustion like ION had). So I don't see adding many differently named heaps as particularly problematic. That said, if there are truly generic properties (cacheable vs non-cachable is maybe one of those) which apply to most heaps, I'm open to making use of the flags. But I want to avoid having per-heap flags, it really needs to be a generic attribute. And I personally don't mind the idea of having things added as heaps initially, and potentially upgrading them to flags if needed (allowing heap drivers to optionally enumerate the old chardevs behind a config option for backwards compatibility). How common is the hardware that is going to provide this configurable ECC option, and will you really want the option on all of the heap types? Will there be any hardware constraint limitations caused by the ECC/!ECC flags? (ie: Devices that can't use !ECC allocated buffers?) If not, I wonder if it would make sense to have something more along the lines using a fcntl() like how F_SEAL_* is used with memfds? With some of the discussion around "restricted"/"secure" heaps that can change state, I've liked this idea of just allocating dmabufs from normal heaps and then using fcntl or something similar to modify properties of the buffer that are separate from the type of memory that is needed to be allocated to satisfy device constraints. thanks -john

1 year, 6 months

Re: [PATCH 01/18] ASoC: dt-bindings: mediatek,mt8365-afe: Add audio afe document

by AngeloGioacchino Del Regno

Il 28/02/24 10:57, Alexandre Mergnat ha scritto: > I think I got it. > > - mediatek,i2s-shared-clock: will be remove from DT > - mediatek,dmic-iir-on: will be remove from DT > - mediatek,dmic-irr-mode: will be remove from DT > - mediatek,dmic-two-wire-mode: rephrase description needed > > I've did abstraction (despite me) that IIR settings are runtime config because the > driver implement its usage like a one-time-setup -_-' > Yes but just one more thing I just noticed: `mediatek,dmic-two-wire-mode` - can we please rename this to `mediatek,dmic-mode` ? That'd be for consistency check mt6359.yaml and mt6358.txt mediatek,dmic-mode: $ref: /schemas/types.yaml#/definitions/uint32 description: | Indicates how many data pins are used to transmit two channels of PDM signal. 0 means two wires, 1 means one wire. Default value is 0. enum: - 0 # one wire - 1 # two wires Cheers, Angelo > Thanks for the explanations, that help. > > Regards, > Alexandre > > On 28/02/2024 08:28, Krzysztof Kozlowski wrote: >> On 27/02/2024 16:18, Alexandre Mergnat wrote: >>>> >>>>> + type: boolean >>>>> + >>>>> + mediatek,dmic-iir-on: >>>>> + description: >>>>> + Boolean which specifies whether the DMIC IIR is enabled. >>>>> + If this property is not present the IIR is disabled. >>>> >>>> "is enabled" or "enable it"? >>>> >>>> You described the desired Linux feature or behavior, not the actual >>>> hardware. The bindings are about the latter, so instead you need to >>>> rephrase the property and its description to match actual hardware >>>> capabilities/features/configuration etc. >>> >>> I will rephrase: >>> >>> True to enable the Infinite Impulse Response (IIR) filter >>> on the digital microphone inputs. >> >> I still don't know why this is DT-specific. You still tell driver what >> to do... >> >>> >>>> >>>>> + type: boolean >>>>> + >>>>> + mediatek,dmic-irr-mode: >>>>> + $ref: /schemas/types.yaml#/definitions/uint32 >>>>> + description: >>>>> + Selects stop band of IIR DC-removal filter. >>>>> + 0 = Software programmable custom coeff loaded by the driver. >>>> >>>> Bindings are for hardware, not drivers. Why is this a property of board DTS? >>> >>> Actually this is a hardware feature. Mode 1 t 5 are predefined filters. >>> Mode 0, the HW will read some "coef filter registers" to setup the >>> custom filter. the "coef filter regs" are written by the driver. >>> Currently the coef values are hardcoded in the driver. >> >> You don't get the point. Just because you choose some mode it does not >> mean is hardware feature for DT. Sampling frequency done by hardware is >> also "hardware feature", but do you put it to DT? No. >> >> Explain why this is board-specific, not runtime configuration. >> >>> >>>> >>>>> + 1 = 5Hz if 48KHz mode. >>>>> + 2 = 10Hz if 48KHz mode. >>>>> + 3 = 25Hz if 48KHz mode. >>>>> + 4 = 50Hz if 48KHz mode. >>>>> + 5 = 65Hz if 48KHz mode. >>>> >>>> Use proper unit suffixes - hz. >>>> >>>> >>>>> + enum: >>>>> + - 0 >>>>> + - 1 >>>>> + - 2 >>>>> + - 3 >>>>> + - 4 >>>>> + - 5 >>>>> + >>>>> + mediatek,dmic-two-wire-mode: >>>>> + description: >>>>> + Boolean which turns on digital microphone for two wire mode. >>>>> + If this property is not present the two wire mode is disabled. >>>> >>>> This looks like hardware property, but the naming looks like SW. Again >>>> you instruct what driver should do. Standard disclaimer: >>>> >>>> You described the desired Linux feature or behavior, not the actual >>>> hardware. The bindings are about the latter, so instead you need to >>>> rephrase the property and its description to match actual hardware >>>> capabilities/features/configuration etc. >>> >>> Actually this is a hardware feature. This is ALL I have to describe the >>> HW behavior from the datasheet: >>> " >>> bit name: ul_dmic_two_wire_ctl >>> Turns on digital microphone for two wire mode. >>> 0: Turn off >>> 1: Turn on >> >> That's rather suggestion it is not a description of hardware but you >> want driver to do something... >> >>> " >>> >>> On the board schematic, SoC and DMIC and linked by 3 pins: >>> - clk >>> - data0 >>> - data1 >>> >>> IMHO, "two-wire-mode" means the HW use 2 pins for data, and the SoC must >>> be aware of that by reading the register value written by the driver, >>> using the value found in the DTS. >> >> So this depends on type of connection of DMIC? Then rephrase description >> property like this. >> >>> >>> I don't get why you think it wouldn't be hardware behavior. >> >> Because telling what to write to the registers which is typical sign of >> people stuffing to DT whatever they need to configure the hardware. >> >>> >>> Rephrase description: >>> "True to enable the two wire mode of the digital microphone" >>> Is it better ? >> >> No, because again you describe some sort of mode. If you insist on such >> description, then my answer is: it's runtime, so not suitable for DT. >> Instead describe what is the hardware problem/configuration, e.g. "DMIC >> is connected with only CLK and DATA0, without third pin" etc. >> >>> >>> About the property name, "mediatek,dmic-two-wire-ctl" sound better for you ? >> >> To sound more like a register less like physical characteristic of the >> board? No. The name can stay, I don't have better ideas. >> >> >> Best regards, >> Krzysztof >> >

1 year, 6 months

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