| Message ID | 20191215165924.28314-6-wens@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: sun4i-csi: A10/A20 CSI1 and R40 CSI0 support | expand |
On Mon, Dec 16, 2019 at 12:59:15AM +0800, Chen-Yu Tsai wrote: > From: Chen-Yu Tsai <wens@csie.org> > > On Allwinner SoCs, some high memory bandwidth devices do DMA directly > over the memory bus (called MBUS), instead of the system bus. These > devices include the CSI camera sensor interface, video (codec) engine, > display subsystem, etc.. The memory bus has a different addressing > scheme without the DRAM starting offset. > > Deal with this using the "interconnects" property from the device tree, > or if that is not available, set dev->dma_pfn_offset to PHYS_PFN_OFFSET. > > Fixes: 577bbf23b758 ("media: sunxi: Add A10 CSI driver") > Signed-off-by: Chen-Yu Tsai <wens@csie.org> Acked-by: Maxime Ripard <mripard@kernel.org> > --- > .../platform/sunxi/sun4i-csi/sun4i_csi.c | 22 +++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c > index f36dc6258900..b8b07c1de2a8 100644 > --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c > +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c > @@ -11,6 +11,7 @@ > #include <linux/module.h> > #include <linux/mutex.h> > #include <linux/of.h> > +#include <linux/of_device.h> > #include <linux/of_graph.h> > #include <linux/platform_device.h> > #include <linux/pm_runtime.h> > @@ -155,6 +156,27 @@ static int sun4i_csi_probe(struct platform_device *pdev) > subdev = &csi->subdev; > vdev = &csi->vdev; > > + /* > + * On Allwinner SoCs, some high memory bandwidth devices do DMA > + * directly over the memory bus (called MBUS), instead of the > + * system bus. The memory bus has a different addressing scheme > + * without the DRAM starting offset. > + * > + * In some cases this can be described by an interconnect in > + * the device tree. In other cases where the hardware is not > + * fully understood and the interconnect is left out of the > + * device tree, fall back to a default offset. > + */ Though we should probably mention the DT-backward-compatibility case here too. Maxime
diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c index f36dc6258900..b8b07c1de2a8 100644 --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/of.h> +#include <linux/of_device.h> #include <linux/of_graph.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> @@ -155,6 +156,27 @@ static int sun4i_csi_probe(struct platform_device *pdev) subdev = &csi->subdev; vdev = &csi->vdev; + /* + * On Allwinner SoCs, some high memory bandwidth devices do DMA + * directly over the memory bus (called MBUS), instead of the + * system bus. The memory bus has a different addressing scheme + * without the DRAM starting offset. + * + * In some cases this can be described by an interconnect in + * the device tree. In other cases where the hardware is not + * fully understood and the interconnect is left out of the + * device tree, fall back to a default offset. + */ + if (of_find_property(csi->dev->of_node, "interconnects", NULL)) { + ret = of_dma_configure(csi->dev, csi->dev->of_node, true); + if (ret) + return ret; + } else { +#ifdef PHYS_PFN_OFFSET + csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET; +#endif + } + csi->mdev.dev = csi->dev; strscpy(csi->mdev.model, "Allwinner Video Capture Device", sizeof(csi->mdev.model));