-----Original Message----- From: Ulf Hansson ulf.hansson@linaro.org Sent: 2020年4月1日 2:39 To: Greg Kroah-Hartman gregkh@linuxfoundation.org; Rafael J . Wysocki rafael@kernel.org; linux-kernel@vger.kernel.org Cc: Arnd Bergmann arnd@arndb.de; Christoph Hellwig hch@lst.de; Russell King linux@armlinux.org.uk; Linus Walleij linus.walleij@linaro.org; Robin Murphy robin.murphy@arm.com; Vinod Koul vkoul@kernel.org; BOUGH CHEN haibo.chen@nxp.com; Ludovic Barre ludovic.barre@st.com; linux-arm-kernel@lists.infradead.org; dmaengine@vger.kernel.org; Ulf Hansson ulf.hansson@linaro.org; stable@vger.kernel.org Subject: [PATCH v2 1/2] 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().
Suggested-by: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Signed-off-by: Ulf Hansson ulf.hansson@linaro.org
Hi Ulf,
I test both on our local 5.4.24 branch and the latest Linux-next, both works fine.
Tested-by: Haibo Chen haibo.chen@nxp.com
Best Regards Haibo Chen
Changes in v2:
- Move initialization to setup_pdev_dma_masks(). This means the
initialization is done also in the OF path.
drivers/base/platform.c | 2 ++ include/linux/platform_device.h | 1 + 2 files changed, 3 insertions(+)
diff --git a/drivers/base/platform.c b/drivers/base/platform.c index b5ce7b085795..c81b68d5d66d 100644 --- 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) {
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;
-- 2.20.1