Hi Arun, On Tuesday 22 April 2014 17:52:08 Arun Kumar K wrote: > On Tue, Apr 22, 2014 at 5:23 PM, Laurent Pinchart wrote: > > On Tuesday 22 April 2014 16:32:48 Arun Kumar K wrote: > >> The patch adds IOMMU support for MFC driver. > > > > I've been working on an IOMMU driver lately, which led me to think about > > how drivers should be interfaced with IOMMUs. Runtime IOMMU handling is > > performed by the DMA mapping API, but in many cases (including Exynos > > platforms) the arm_iommu_create_mapping() and arm_iommu_attach_device() > > functions still need to be called explicitly by drivers, which doesn't > > seem a very good idea to me. Ideally IOMMU usage should be completely > > transparent for bus master drivers, without requiring any driver > > modification to use the IOMMU. > > > > What would you think about improving the Exynos IOMMU driver to create the > > mapping and attach the device instead of having to modify all bus master > > drivers ? See the ipmmu_add_device() function in > > http://www.spinics.net/lists/linux-sh/msg30488.html for a possible > > implementation. > > Yes that would be a better solution. But as far as I know, exynos platforms > has few more complications where multiple IOMMUs are present for single IP. > The exynos iommu work is still under progress and KyonHo Cho will have some > inputs / comments on this. This seems to me a valid usecase which can be > considered for exynos iommu also. Thank you. Just to be clear, I don't see a reason to delay this patch until the Exynos IOMMU driver gets support for creating mappings and attaching devices, but it would be nice to see that happen as a cleanup in the not too distant future. > >> Signed-off-by: Arun Kumar K <arun.kk@xxxxxxxxxxx> > >> --- > >> This patch is tested on IOMMU support series [1] posted > >> by KyonHo Cho. > >> [1] https://lkml.org/lkml/2014/3/14/9 > >> --- > >> > >> drivers/media/platform/s5p-mfc/s5p_mfc.c | 33 > >> +++++++++++++++++++++++++++ > >> 1 file changed, 33 insertions(+) > >> > >> diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c > >> b/drivers/media/platform/s5p-mfc/s5p_mfc.c index 89356ae..1f248ba 100644 > >> --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c > >> +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c > >> @@ -32,11 +32,18 @@ > >> > >> #include "s5p_mfc_opr.h" > >> #include "s5p_mfc_cmd.h" > >> #include "s5p_mfc_pm.h" > >> > >> +#ifdef CONFIG_EXYNOS_IOMMU > >> +#include <asm/dma-iommu.h> > >> +#endif > >> > >> #define S5P_MFC_NAME "s5p-mfc" > >> #define S5P_MFC_DEC_NAME "s5p-mfc-dec" > >> #define S5P_MFC_ENC_NAME "s5p-mfc-enc" > >> > >> +#ifdef CONFIG_EXYNOS_IOMMU > >> +static struct dma_iommu_mapping *mapping; > >> +#endif > >> + > >> > >> int debug; > >> module_param(debug, int, S_IRUGO | S_IWUSR); > >> MODULE_PARM_DESC(debug, "Debug level - higher value produces more > >> verbose > >> > >> messages"); @@ -1013,6 +1020,23 @@ static void *mfc_get_drv_data(struct > >> platform_device *pdev); > >> > >> static int s5p_mfc_alloc_memdevs(struct s5p_mfc_dev *dev) > >> { > >> > >> +#ifdef CONFIG_EXYNOS_IOMMU > >> + struct device *mdev = &dev->plat_dev->dev; > >> + > >> + mapping = arm_iommu_create_mapping(&platform_bus_type, 0x20000000, > >> + SZ_256M); > >> + if (mapping == NULL) { > >> + mfc_err("IOMMU mapping failed\n"); > >> + return -EFAULT; > >> + } > >> + mdev->dma_parms = devm_kzalloc(&dev->plat_dev->dev, > >> + sizeof(*mdev->dma_parms), GFP_KERNEL); > >> + dma_set_max_seg_size(mdev, 0xffffffffu); > >> + arm_iommu_attach_device(mdev, mapping); > >> + > >> + dev->mem_dev_l = dev->mem_dev_r = mdev; > >> + return 0; > >> +#else > >> > >> unsigned int mem_info[2] = { }; > >> > >> dev->mem_dev_l = devm_kzalloc(&dev->plat_dev->dev, > >> > >> @@ -1049,6 +1073,7 @@ static int s5p_mfc_alloc_memdevs(struct s5p_mfc_dev > >> *dev) return -ENOMEM; > >> > >> } > >> return 0; > >> > >> +#endif > >> > >> } > >> > >> /* MFC probe function */ > >> > >> @@ -1228,6 +1253,10 @@ err_mem_init_ctx_1: > >> vb2_dma_contig_cleanup_ctx(dev->alloc_ctx[0]); > >> > >> err_res: > >> s5p_mfc_final_pm(dev); > >> > >> +#ifdef CONFIG_EXYNOS_IOMMU > >> + if (mapping) > >> + arm_iommu_release_mapping(mapping); > >> +#endif > >> > >> pr_debug("%s-- with error\n", __func__); > >> return ret; > >> > >> @@ -1256,6 +1285,10 @@ static int s5p_mfc_remove(struct platform_device > >> *pdev) put_device(dev->mem_dev_r); > >> > >> } > >> > >> +#ifdef CONFIG_EXYNOS_IOMMU > >> + if (mapping) > >> + arm_iommu_release_mapping(mapping); > >> +#endif > >> > >> s5p_mfc_final_pm(dev); > >> return 0; > >> > >> } -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
