[PATCH] radeon: workaround pining failure on low ram gpu

[Alex Deucher]

On Tue, Nov 12, 2013 at 10:51 AM,  <j.glisse at gmail.com> wrote:
> From: Jerome Glisse <jglisse at redhat.com>
>
> GPU with low amount of ram can fails at pining new framebuffer before
> unpining old one. On such failure, retry with unping old one before
> pining new one allowing to work around the issue. This is somewhat
> ugly but only affect those old GPU we care about.
>
> Signed-off-by: Jerome Glisse <jglisse at redhat.com>

Added to my queue and added stable cc.

Thanks!

> ---
>  drivers/gpu/drm/radeon/radeon_legacy_crtc.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_legacy_crtc.c b/drivers/gpu/drm/radeon/radeon_legacy_crtc.c
> index 0c7b8c6..0b158f9 100644
> --- a/drivers/gpu/drm/radeon/radeon_legacy_crtc.c
> +++ b/drivers/gpu/drm/radeon/radeon_legacy_crtc.c
> @@ -422,6 +422,7 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
>         /* Pin framebuffer & get tilling informations */
>         obj = radeon_fb->obj;
>         rbo = gem_to_radeon_bo(obj);
> +retry:
>         r = radeon_bo_reserve(rbo, false);
>         if (unlikely(r != 0))
>                 return r;
> @@ -430,6 +431,33 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
>                                      &base);
>         if (unlikely(r != 0)) {
>                 radeon_bo_unreserve(rbo);
> +
> +               /* On old GPU like RN50 with little vram pining can fails because
> +                * current fb is taking all space needed. So instead of unpining
> +                * the old buffer after pining the new one, first unpin old one
> +                * and then retry pining new one.
> +                *
> +                * As only master can set mode only master can pin and it is
> +                * unlikely the master client will race with itself especialy
> +                * on those old gpu with single crtc.
> +                *
> +                * We don't shutdown the display controller because new buffer
> +                * will end up in same spot.
> +                */
> +               if (!atomic && fb && fb != crtc->fb) {
> +                       struct radeon_bo *old_rbo;
> +                       unsigned long nsize, osize;
> +
> +                       old_rbo = gem_to_radeon_bo(to_radeon_framebuffer(fb)->obj);
> +                       osize = radeon_bo_size(old_rbo);
> +                       nsize = radeon_bo_size(rbo);
> +                       if (nsize <= osize && !radeon_bo_reserve(old_rbo, false)) {
> +                               radeon_bo_unpin(old_rbo);
> +                               radeon_bo_unreserve(old_rbo);
> +                               fb = NULL;
> +                               goto retry;
> +                       }
> +               }
>                 return -EINVAL;
>         }
>         radeon_bo_get_tiling_flags(rbo, &tiling_flags, NULL);
> --
> 1.8.3.1
>
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