Hi Laurent, Thank you for the review. On Tue, Apr 22, 2014 at 5:23 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Arun, > > Thank you for the patch. > > 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. Regards Arun >> 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
