Re: patch "driver core: platform: Initialize dma_parms for platform devices" added to char-misc-testing

On Thu, 26 Mar 2020 at 15:58, gregkh@linuxfoundation.org wrote:

This is a note to let you know that I've just added the patch titled

driver core: platform: Initialize dma_parms for platform devices

to my char-misc git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git in the char-misc-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the char-misc-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

Greg, would you mind dropping this one and the other patch for the amba bus?

I just sent out a new version (v2), addressing an issue for the platform device when used for OF based platforms.

If you prefer to not rebase/drop patches from your branch, I can send an incremental change on top instead, whatever you prefer.

Kind regards Uffe

From 7c8978c0837d40c302f5e90d24c298d9ca9fc097 Mon Sep 17 00:00:00 2001 From: Ulf Hansson ulf.hansson@linaro.org Date: Wed, 25 Mar 2020 12:34:06 +0100 Subject: driver core: platform: Initialize dma_parms for platform devices

It's currently the platform driver's responsibility to initialize the pointer, dma_parms, for its corresponding struct device. The benefit with this approach allows us to avoid the initialization and to not waste memory for the struct device_dma_parameters, as this can be decided on a case by case basis.

However, it has turned out that this approach is not very practical. Not only does it lead to open coding, but also to real errors. In principle callers of dma_set_max_seg_size() doesn't check the error code, but just assumes it succeeds.

For these reasons, let's do the initialization from the common platform bus at the device registration point. This also follows the way the PCI devices are being managed, see pci_device_add().

Cc: stable@vger.kernel.org Suggested-by: Christoph Hellwig hch@lst.de Tested-by: Ludovic Barre ludovic.barre@st.com Reviewed-by: Linus Walleij linus.walleij@linaro.org Acked-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Link: https://lore.kernel.org/r/20200325113407.26996-2-ulf.hansson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

---

drivers/base/platform.c | 1 + include/linux/platform_device.h | 1 + 2 files changed, 2 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c index b5ce7b085795..46abbfb52655 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -512,6 +512,7 @@ int platform_device_add(struct platform_device *pdev) pdev->dev.parent = &platform_bus;

    pdev->dev.bus = &platform_bus_type;

•   pdev->dev.dma_parms = &pdev->dma_parms;
  
    switch (pdev->id) {
    default:
  

diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 041bfa412aa0..81900b3cbe37 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -25,6 +25,7 @@ struct platform_device { bool id_auto; struct device dev; u64 platform_dma_mask;

•   struct device_dma_parameters dma_parms;
    u32             num_resources;
    struct resource *resource;
  
  

-- 2.26.0