[PATCH 0/8] drm/tegra: Fixes for v3.19-rc1

[Sean Paul]

On Tue, Dec 16, 2014 at 11:15 AM, Thierry Reding
<thierry.reding at gmail.com> wrote:
> From: Thierry Reding <treding at nvidia.com>
>
> Hi,
>
> This is a set of fixes for two regressions and one bug in the IOMMU
> mapping code. It turns out that all of these issues turn up primarily
> on Tegra30 hardware. The IOMMU mapping bug only manifests on buffers
> that aren't multiples of the page size. I happened to be testing HDMI
> with 1080p while writing the code and framebuffers for that happen to
> fit exactly within 2025 pages of 4 KiB each.
>
> One of the regressions is caused by the IOMMU code allocating pages from
> shmem which can have associated cache lines. If the pages aren't flushed
> then these cache lines may be flushed later on and cause framebuffer
> corruption. I'm not sure why I didn't see this before. Perhaps the board
> that I was using had enough RAM so that the pages shmem would hand out
> had a better chance of being unused. Or maybe I didn't look too closely.
> The fix for this, implementing drm_clflush_*() for ARM, has also been
> tested by Rob. The long-term plan is to make architectures expose an API
> to flush pages, but for now drm_clflush_*() provides exactly what we
> need.
>
> The second regression is caused by a mismatch between the hardware pipe
> number and the CRTC's DRM index. These were used inconsistently, which
> could cause one code location to call drm_vblank_get() with a different
> pipe than the corresponding drm_vblank_put(), thereby causing the
> reference count to become unbalanced. Alexandre also reported a possible
> race condition related to this, which this series also fixes.
>
> I'm hoping to get reviews on this, especially the drm/irq and drm/cache
> patches, quickly so that I can send a pull request to Dave, hopefully to
> get this included, given the size, in v3.19-rc1 still.
>

Hi Thierry,
Have you made a determination on "drm/tegra: Select root window for
event dispatch"? The bug it fixes makes concurrent flips and overlay
updates impossible.

Sean


> Thierry
>
> Thierry Reding (8):
>   drm/irq: Add drm_crtc_send_vblank_event()
>   drm/irq: Add drm_crtc_handle_vblank()
>   drm/irq: Add drm_crtc_vblank_count()
>   drm/tegra: dc: Consistently use the same pipe
>   drm/tegra: dc: Fix a potential race on page-flip completion
>   drm/cache: Implement drm_clflush_*() for ARM
>   drm/tegra: gem: Flush buffer objects upon allocation
>   drm/tegra: gem: Use the proper size for GEM objects
>
>  drivers/gpu/drm/drm_cache.c | 45 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_irq.c   | 60 +++++++++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/tegra/dc.c  | 24 ++++++++++--------
>  drivers/gpu/drm/tegra/drm.c | 16 +++++++-----
>  drivers/gpu/drm/tegra/gem.c | 16 ++++++------
>  include/drm/drmP.h          |  4 +++
>  6 files changed, 142 insertions(+), 23 deletions(-)
>
> --
> 2.1.3
>
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