Hi Vikas, On Friday 02 of August 2013 12:08:52 Vikas Sajjan wrote: > Hi Rob, > > On 2 August 2013 06:03, Rob Clark <robdcl...@gmail.com> wrote: > > On Thu, Aug 1, 2013 at 7:20 PM, Tomasz Figa <tomasz.f...@gmail.com> wrote: > >> Hi Vikas, > >> > >> On Thursday 01 of August 2013 16:49:32 Vikas Sajjan wrote: > >>> While trying to get boot-logo up on exynos5420 SMDK which has eDP > >>> panel > >>> connected with resolution 2560x1600, following error occured even > >>> with > >>> IOMMU enabled: > >>> [0.880000] [drm:lowlevel_buffer_allocate] *ERROR* failed to allocate > >>> buffer. [0.890000] [drm] Initialized exynos 1.0.0 20110530 on minor > >>> 0 > >>> > >>> This patch fixes the issue by adding a check for IOMMU. > >>> > >>> Signed-off-by: Vikas Sajjan <vikas.saj...@linaro.org> > >>> Signed-off-by: Arun Kumar <arun...@samsung.com> > >>> --- > >>> > >>> drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 9 ++++++++- > >>> 1 file changed, 8 insertions(+), 1 deletion(-) [snip] > >>> @@ -166,7 +168,12 @@ static int exynos_drm_fbdev_create(struct > >>> drm_fb_helper *helper, size = mode_cmd.pitches * mode_cmd.height; > >>> > >>> /* 0 means to allocate physically continuous memory */ > >>> > >>> - exynos_gem_obj = exynos_drm_gem_create(dev, 0, size); > >>> + if (!is_drm_iommu_supported(dev)) > >>> + flag = 0; > >>> + else > >>> + flag = EXYNOS_BO_NONCONTIG; > >> > >> While noncontig memory might be used for devices that support IOMMU, > >> there should be no problem with using contig memory for them, so > >> this seems more like masking the original problem rather than > >> tracking it down.> > > it is probably a good idea to not require contig memory when it is not > > needed for performance or functionality (and if it is only > > performance, then fallback gracefully to non-contig).. but yeah, would > > be good to know if this is masking another issue all the same > > Whats happening with CONTIG flag and with IOMMU, is > > __iommu_alloc_buffer() ---> dma_alloc_from_contiguous() and in this > function it fails at > this condition check if (pageno >= cma->count) > > So I tried increasing the CONFIG_CMA_SIZE_MBYTES to 24, this check > succeeds and it works well without my patch. > > But what about the case where CONFIG_CMA is disabled , yet i want > bigger memory for a device. > I think using IOMMU we can achieve this. > > correct me, if i am wrong.
This is probably fine. I'm not sure about performance aspects of using noncontig memory as framebuffer, though. This needs to be checked and if there is some performance penalty, I would make noncontig allocation a fallback case, if contig fails, as Rob has suggested. Also I think you should adjust the commit message to say that non- contiguous memory can be used when IOMMU is supported, so there is no need to force contiguous allocations, since this is not a bug fix, but rather a feature this patch is adding. Best regards, Tomasz > > BR, > > -R > > > >> Could you check why the allocation fails when requesting contiguous > >> memory? > >> > >> Best regards, > >> Tomasz > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe > >> linux-media" in the body of a message to majord...@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html