On 10/19/2016 08:16 AM, Inki Dae wrote: > Hi Shuah, > > 2016-10-13 8:11 GMT+09:00 Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>: >> Hi Inki, >> >> On 08/15/2016 10:40 PM, Inki Dae wrote: >> >>>> >>>> okay the very first commit that added IOMMU support >>>> introduced the code that rejects non-contig gem memory >>>> type without IOMMU. >>>> >>>> commit 0519f9a12d0113caab78980c48a7902d2bd40c2c >>>> Author: Inki Dae <inki.dae@xxxxxxxxxxx> >>>> Date: Sat Oct 20 07:53:42 2012 -0700 >>>> >>>> drm/exynos: add iommu support for exynos drm framework >>>> >> >> I haven't given up on this yet. I am still seeing the following failure: >> >> Additional debug messages I added: >> [ 15.287403] exynos_drm_gem_create_ioctl() 1 >> [ 15.287419] exynos_drm_gem_create() flags 1 >> >> [ 15.311511] [drm:exynos_drm_framebuffer_init] *ERROR* Non-contiguous GEM memory is not supported. >> >> Additional debug message I added: >> [ 15.318981] [drm:exynos_user_fb_create] *ERROR* failed to initialize framebuffer >> >> This is what happens: >> >> 1. exynos_drm_gem_create_ioctl() gets called with EXYNOS_BO_NONCONTIG request >> 2. exynos_drm_gem_create(0 goes ahead and creates the GEM buffers >> 3. exynos_user_fb_create() tries to associate GEM to fb and fails during >> check_fb_gem_memory_type() >> >> At this point, there is no recovery and lightdm fails >> >> xf86-video-armsoc/src/drmmode_exynos/drmmode_exynos.c assumes contiguous >> allocations are not supported in some exynos drm versions: The following >> commit introduced this change: >> >> https://git.linaro.org/arm/xorg/driver/xf86-video-armsoc.git/commitdiff/3be1f6273441fe95dd442f44064387322e16b7e9 >> >> excerpts from the diff:- if (create_gem->buf_type == ARMSOC_BO_SCANOUT) >> - create_exynos.flags = EXYNOS_BO_CONTIG; >> - else >> - create_exynos.flags = EXYNOS_BO_NONCONTIG; >> + >> + /* Contiguous allocations are not supported in some exynos drm versions. >> + * When they are supported all allocations are effectively contiguous >> + * anyway, so for simplicity we always request non contiguous buffers. >> + */ >> + create_exynos.flags = EXYNOS_BO_NONCONTIG; >> > > Above comment, "Contiguous allocations are not supported in some > exynos drm versions.", seems wrong assumption. > The root cause, contiguous allocation is not supported, would be that > they used Linux kernel which didn't have CMA region enough - as > default 16MB, or didn't declare CMA region enough for the DMA device. > So I think they should not force to flag EXYNOS_BO_NONCONTIG and they > should manage the error case if the allocation failed. This assumption doesn't sound correct and forcing NONCONTIG isn't right either. > >> There might have been logic on exynos_drm that forced Contig when it coudn't >> support NONCONTIG. At least, that is what this comment suggests. This assumption >> doesn't appear to be a good one and not sure if this change was made to fix a bug. >> >> After the IOMMU support, this assumption is no longer true. Hence, with IOMMU >> support, latest kernels have a mismatch with the installed xf86-video-armsoc >> >> This is what I am running into. This leads to the following question: >> >> 1. How do we ensure exynos_drm kernel changes don't break user-space >> specifically xf86-video-armsoc >> 2. This seems to have gone undetected for a while. I see a change in >> exynos_drm_gem_dumb_create() that is probably addressing this type >> of breakage. Commit 122beea84bb90236b1ae545f08267af58591c21b adds >> handling for IOMMU NONCONTIG case. > > Seems this patch has a problem. This patch forces to flag NONCONTIG if > iommu is enabled. The flag should be depend on the argument from > user-space. > I.e., if user-space requested a gem allocation with CONTIG flag, then > Exynos drm driver should allocate contiguous memory even though iommu > is enabled. > >> >> Anyway, I am interested in getting the exynos_drm kernel side code >> and xf86-video-armsoc in sync to resolve the issue. >> >> Could you recommend a going forward plan? > > My opinion are, > > 1. Do not force to flag EXYNOS_BO_NONCONTIG at xf86-video-armsoc > 2. Do not force to flag NONCONTIG at Exynos drm driver even though > iommu is enabled and flag allocation type with the argument from > user-space. > > I think you could try to post above patches. > Sounds good. I will work on the above two patches. thanks, -- Shuah -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |