From: Ulf Hansson <ulf.hansson@xxxxxxxxxx> commit 9495b7e92f716ab2bd6814fab5e97ab4a39adfdd upstream. 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@xxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Tested-by: Haibo Chen <haibo.chen@xxxxxxx> Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Link: https://lore.kernel.org/r/20200422100954.31211-1-ulf.hansson@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/base/platform.c | 2 ++ include/linux/platform_device.h | 1 + 2 files changed, 3 insertions(+) --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -361,6 +361,8 @@ 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) { --- 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;
