Re: [PATCH v2 1/2] media: nxp: imx8-isi: m2m: Fix streaming cleanup on release

On Thu, Aug 21, 2025 at 04:51:22PM +0300, Laurent Pinchart wrote:

From: Guoniu Zhou guoniu.zhou@nxp.com

If streamon/streamoff calls are imbalanced, such as when exiting an application with Ctrl+C when streaming, the m2m usage_count will never reach zero and the ISI channel won't be freed. Besides from that, if the input line width is more than 2K, it will trigger a WARN_ON():

[ 59.222120] ------------[ cut here ]------------ [ 59.226758] WARNING: drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c:631 at mxc_isi_channel_chain+0xa4/0x120, CPU#4: v4l2-ctl/654 [ 59.238569] Modules linked in: ap1302 [ 59.242231] CPU: 4 UID: 0 PID: 654 Comm: v4l2-ctl Not tainted 6.16.0-rc4-next-20250704-06511-gff0e002d480a-dirty #258 PREEMPT [ 59.253597] Hardware name: NXP i.MX95 15X15 board (DT) [ 59.258720] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 59.265669] pc : mxc_isi_channel_chain+0xa4/0x120 [ 59.270358] lr : mxc_isi_channel_chain+0x44/0x120 [ 59.275047] sp : ffff8000848c3b40 [ 59.278348] x29: ffff8000848c3b40 x28: ffff0000859b4c98 x27: ffff800081939f00 [ 59.285472] x26: 000000000000000a x25: ffff0000859b4cb8 x24: 0000000000000001 [ 59.292597] x23: ffff0000816f4760 x22: ffff0000816f4258 x21: ffff000084ceb780 [ 59.299720] x20: ffff000084342ff8 x19: ffff000084340000 x18: 0000000000000000 [ 59.306845] x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffdb369e1c [ 59.313969] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 [ 59.321093] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 [ 59.328217] x8 : ffff8000848c3d48 x7 : ffff800081930b30 x6 : ffff800081930b30 [ 59.335340] x5 : ffff0000859b6000 x4 : ffff80008193ae80 x3 : ffff800081022420 [ 59.342464] x2 : ffff0000852f6900 x1 : 0000000000000001 x0 : ffff000084341000 [ 59.349590] Call trace: [ 59.352025] mxc_isi_channel_chain+0xa4/0x120 (P) [ 59.356722] mxc_isi_m2m_streamon+0x160/0x20c [ 59.361072] v4l_streamon+0x24/0x30 [ 59.364556] __video_do_ioctl+0x40c/0x4a0 [ 59.368560] video_usercopy+0x2bc/0x690 [ 59.372382] video_ioctl2+0x18/0x24 [ 59.375857] v4l2_ioctl+0x40/0x60 [ 59.379168] __arm64_sys_ioctl+0xac/0x104 [ 59.383172] invoke_syscall+0x48/0x104 [ 59.386916] el0_svc_common.constprop.0+0xc0/0xe0 [ 59.391613] do_el0_svc+0x1c/0x28 [ 59.394915] el0_svc+0x34/0xf4 [ 59.397966] el0t_64_sync_handler+0xa0/0xe4 [ 59.402143] el0t_64_sync+0x198/0x19c [ 59.405801] ---[ end trace 0000000000000000 ]---

Address this issue by moving the streaming preparation and cleanup to the vb2 .prepare_streaming() and .unprepare_streaming() operations. This also simplifies the driver by allowing direct usage of the v4l2_m2m_ioctl_streamon() and v4l2_m2m_ioctl_streamoff() helpers.

Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver") Cc: stable@vger.kernel.org Signed-off-by: Guoniu Zhou guoniu.zhou@nxp.com Co-developed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com

Reviewed-by: Frank Li Frank.Li@nxp.com

---

.../platform/nxp/imx8-isi/imx8-isi-m2m.c | 224 +++++++----------- 1 file changed, 92 insertions(+), 132 deletions(-)

diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c index 6bdd13b3048f..a8b10d944d69 100644 --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c @@ -43,7 +43,6 @@ struct mxc_isi_m2m_ctx_queue_data { struct v4l2_pix_format_mplane format; const struct mxc_isi_format_info *info; u32 sequence;

• bool streaming;

};

struct mxc_isi_m2m_ctx { @@ -236,6 +235,65 @@ static void mxc_isi_m2m_vb2_buffer_queue(struct vb2_buffer *vb2) v4l2_m2m_buf_queue(ctx->fh.m2m_ctx, vbuf); }

+static int mxc_isi_m2m_vb2_prepare_streaming(struct vb2_queue *q) +{

• struct mxc_isi_m2m_ctx *ctx = vb2_get_drv_priv(q);
• const struct v4l2_pix_format_mplane *out_pix = &ctx->queues.out.format;
• const struct v4l2_pix_format_mplane *cap_pix = &ctx->queues.cap.format;
• const struct mxc_isi_format_info *cap_info = ctx->queues.cap.info;
• const struct mxc_isi_format_info *out_info = ctx->queues.out.info;
• struct mxc_isi_m2m *m2m = ctx->m2m;
• int ret;
• guard(mutex)(&m2m->lock);
• if (m2m->usage_count == INT_MAX)

• return -EOVERFLOW;
  

• /*

• * Acquire the pipe and initialize the channel with the first user of
  

• * the M2M device.
  

• */
  

• if (m2m->usage_count == 0) {

• bool bypass = cap_pix->width == out_pix->width &&
  

• 	      cap_pix->height == out_pix->height &&
  

• 	      cap_info->encoding == out_info->encoding;
  

• ret = mxc_isi_channel_acquire(m2m->pipe,
  

• 			      &mxc_isi_m2m_frame_write_done,
  

• 			      bypass);
  

• if (ret)
  

• 	return ret;
  

• mxc_isi_channel_get(m2m->pipe);
  

• }
• m2m->usage_count++;
• /*

• * Allocate resources for the channel, counting how many users require
  

• * buffer chaining.
  

• */
  

• if (!ctx->chained && out_pix->width > MXC_ISI_MAX_WIDTH_UNCHAINED) {

• ret = mxc_isi_channel_chain(m2m->pipe);
  

• if (ret)
  

• 	goto err_deinit;
  

• m2m->chained_count++;
  

• ctx->chained = true;
  

• }
• return 0;

+err_deinit:

• if (--m2m->usage_count == 0) {

• mxc_isi_channel_put(m2m->pipe);
  

• mxc_isi_channel_release(m2m->pipe);
  

• }
• return ret;

+}

static int mxc_isi_m2m_vb2_start_streaming(struct vb2_queue *q, unsigned int count) { @@ -265,13 +323,44 @@ static void mxc_isi_m2m_vb2_stop_streaming(struct vb2_queue *q) } }

+static void mxc_isi_m2m_vb2_unprepare_streaming(struct vb2_queue *q) +{

• struct mxc_isi_m2m_ctx *ctx = vb2_get_drv_priv(q);
• struct mxc_isi_m2m *m2m = ctx->m2m;
• guard(mutex)(&m2m->lock);
• /*

• * If the last context is this one, reset it to make sure the device
  

• * will be reconfigured when streaming is restarted.
  

• */
  

• if (m2m->last_ctx == ctx)

• m2m->last_ctx = NULL;
  

• /* Free the channel resources if this is the last chained context. */
• if (ctx->chained && --m2m->chained_count == 0)

• mxc_isi_channel_unchain(m2m->pipe);
  

• ctx->chained = false;
• /* Turn off the light with the last user. */
• if (--m2m->usage_count == 0) {

• mxc_isi_channel_disable(m2m->pipe);
  

• mxc_isi_channel_put(m2m->pipe);
  

• mxc_isi_channel_release(m2m->pipe);
  

• }
• WARN_ON(m2m->usage_count < 0);

+}

static const struct vb2_ops mxc_isi_m2m_vb2_qops = { .queue_setup = mxc_isi_m2m_vb2_queue_setup, .buf_init = mxc_isi_m2m_vb2_buffer_init, .buf_prepare = mxc_isi_m2m_vb2_buffer_prepare, .buf_queue = mxc_isi_m2m_vb2_buffer_queue,

• .prepare_streaming = mxc_isi_m2m_vb2_prepare_streaming, .start_streaming = mxc_isi_m2m_vb2_start_streaming, .stop_streaming = mxc_isi_m2m_vb2_stop_streaming,
• .unprepare_streaming = mxc_isi_m2m_vb2_unprepare_streaming,

};

static int mxc_isi_m2m_queue_init(void *priv, struct vb2_queue *src_vq, @@ -481,135 +570,6 @@ static int mxc_isi_m2m_s_fmt_vid(struct file *file, void *fh, return 0; }

-static int mxc_isi_m2m_streamon(struct file *file, void *fh,

• 		enum v4l2_buf_type type)
  

-{

• struct mxc_isi_m2m_ctx *ctx = file_to_isi_m2m_ctx(file);
• struct mxc_isi_m2m_ctx_queue_data *q = mxc_isi_m2m_ctx_qdata(ctx, type);
• const struct v4l2_pix_format_mplane *out_pix = &ctx->queues.out.format;
• const struct v4l2_pix_format_mplane *cap_pix = &ctx->queues.cap.format;
• const struct mxc_isi_format_info *cap_info = ctx->queues.cap.info;
• const struct mxc_isi_format_info *out_info = ctx->queues.out.info;
• struct mxc_isi_m2m *m2m = ctx->m2m;
• int ret;
• if (q->streaming)

• return 0;
  

• mutex_lock(&m2m->lock);
• if (m2m->usage_count == INT_MAX) {

• ret = -EOVERFLOW;
  

• goto unlock;
  

• }
• /*

• * Acquire the pipe and initialize the channel with the first user of
  

• * the M2M device.
  

• */
  

• if (m2m->usage_count == 0) {

• bool bypass = cap_pix->width == out_pix->width &&
  

• 	      cap_pix->height == out_pix->height &&
  

• 	      cap_info->encoding == out_info->encoding;
  

• ret = mxc_isi_channel_acquire(m2m->pipe,
  

• 			      &mxc_isi_m2m_frame_write_done,
  

• 			      bypass);
  

• if (ret)
  

• 	goto unlock;
  

• mxc_isi_channel_get(m2m->pipe);
  

• }
• m2m->usage_count++;
• /*

• * Allocate resources for the channel, counting how many users require
  

• * buffer chaining.
  

• */
  

• if (!ctx->chained && out_pix->width > MXC_ISI_MAX_WIDTH_UNCHAINED) {

• ret = mxc_isi_channel_chain(m2m->pipe);
  

• if (ret)
  

• 	goto deinit;
  

• m2m->chained_count++;
  

• ctx->chained = true;
  

• }
• /*

• * Drop the lock to start the stream, as the .device_run() operation
  

• * needs to acquire it.
  

• */
  

• mutex_unlock(&m2m->lock);
• ret = v4l2_m2m_ioctl_streamon(file, fh, type);
• if (ret) {

• /* Reacquire the lock for the cleanup path. */
  

• mutex_lock(&m2m->lock);
  

• goto unchain;
  

• }
• q->streaming = true;
• return 0;

-unchain:

• if (ctx->chained && --m2m->chained_count == 0)

• mxc_isi_channel_unchain(m2m->pipe);
  

• ctx->chained = false;

-deinit:

• if (--m2m->usage_count == 0) {

• mxc_isi_channel_put(m2m->pipe);
  

• mxc_isi_channel_release(m2m->pipe);
  

• }

-unlock:

• mutex_unlock(&m2m->lock);
• return ret;

-}

-static int mxc_isi_m2m_streamoff(struct file *file, void *fh,

• 		 enum v4l2_buf_type type)
  

-{

• struct mxc_isi_m2m_ctx *ctx = file_to_isi_m2m_ctx(file);
• struct mxc_isi_m2m_ctx_queue_data *q = mxc_isi_m2m_ctx_qdata(ctx, type);
• struct mxc_isi_m2m *m2m = ctx->m2m;
• v4l2_m2m_ioctl_streamoff(file, fh, type);
• if (!q->streaming)

• return 0;
  

• mutex_lock(&m2m->lock);
• /*

• * If the last context is this one, reset it to make sure the device
  

• * will be reconfigured when streaming is restarted.
  

• */
  

• if (m2m->last_ctx == ctx)

• m2m->last_ctx = NULL;
  

• /* Free the channel resources if this is the last chained context. */
• if (ctx->chained && --m2m->chained_count == 0)

• mxc_isi_channel_unchain(m2m->pipe);
  

• ctx->chained = false;
• /* Turn off the light with the last user. */
• if (--m2m->usage_count == 0) {

• mxc_isi_channel_disable(m2m->pipe);
  

• mxc_isi_channel_put(m2m->pipe);
  

• mxc_isi_channel_release(m2m->pipe);
  

• }
• WARN_ON(m2m->usage_count < 0);
• mutex_unlock(&m2m->lock);
• q->streaming = false;
• return 0;

-}

static const struct v4l2_ioctl_ops mxc_isi_m2m_ioctl_ops = { .vidioc_querycap = mxc_isi_m2m_querycap,

@@ -630,8 +590,8 @@ static const struct v4l2_ioctl_ops mxc_isi_m2m_ioctl_ops = { .vidioc_prepare_buf = v4l2_m2m_ioctl_prepare_buf, .vidioc_create_bufs = v4l2_m2m_ioctl_create_bufs,

• .vidioc_streamon = mxc_isi_m2m_streamon,
• .vidioc_streamoff = mxc_isi_m2m_streamoff,

• .vidioc_streamon = v4l2_m2m_ioctl_streamon,

• .vidioc_streamoff = v4l2_m2m_ioctl_streamoff,

  .vidioc_subscribe_event = v4l2_ctrl_subscribe_event, .vidioc_unsubscribe_event = v4l2_event_unsubscribe,

base-commit: a75b8d198c55e9eb5feb6f6e155496305caba2dc prerequisite-patch-id: 9581e075a75aef4b16218280c8dd5788840fad41 prerequisite-patch-id: 74bfb3e362032eae530395b10471ad86175fe592 prerequisite-patch-id: 6c7220d0c283111ab3027086f6ce2d17447e5d07 prerequisite-patch-id: ebefea609f3bd3aacb344701c9971afef5be48ad -- Regards,

Laurent Pinchart