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driver core: platform: Initialize dma_parms for platform devices

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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().

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Tested-by: Haibo Chen <haibo.chen@nxp.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20200422100954.31211-1-ulf.hansson@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ulf Hansson 2020-04-22 12:09:54 +02:00 committed by Greg Kroah-Hartman
parent 6a8b55ed40
commit 9495b7e92f
2 changed files with 3 additions and 0 deletions
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2
drivers/base/platform.c
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@ -380,6 +380,8 @@ struct platform_object {
*/
static void setup_pdev_dma_masks(struct platform_device *pdev)
{
pdev->dev.dma_parms = &pdev->dma_parms;
if (!pdev->dev.coherent_dma_mask)
pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
if (!pdev->dev.dma_mask) {

1
include/linux/platform_device.h
View File

@ -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;