Hi Vikas,
On Friday 02 of August 2013 12:08:52 Vikas Sajjan wrote:
Hi Rob,
On 2 August 2013 06:03, Rob Clark robdclark@gmail.com wrote:
On Thu, Aug 1, 2013 at 7:20 PM, Tomasz Figa tomasz.figa@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.sajjan@linaro.org Signed-off-by: Arun Kumar arun.kk@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[0] * 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;elseflag = 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
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