[Intel-gfx] [PATCH] drm/i915: fbdev_set_par reliably invalidating frontbuffer

[Paulo Zanoni]

2015-07-08 20:24 GMT-03:00 Rodrigo Vivi <rodrigo.vivi at intel.com>:
> fbdev_set_par is called when fbcon is taking over control.
> In the past frontbuffer was being invalidated on
> set_to_gtt_domain, but it moved to set_domain fixing that case,
> but left this behind.
>
> Commit that changed this fixing set_domain case was:
>
> commit 031b698a77a70a6c394568034437b5486a44e868
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Fri Jun 26 19:35:16 2015 +0200
>
>     drm/i915: Unconditionally do fb tracking invalidate in set_domain
>
> Since we are also invalidating in other fbdev cases this one
> was masked here. At least until now that I found this corner
> case: On boot with plymouth doing a splash screen
> when returning to the console frontbuffer wans't being invalidated
> causing missed screen updates with PSR enabled.
>
> So this patch fixes this issue.
>
> v2: Make invalidate directly and unconditionally and
>     fix commit message indicating the set_domain fix
>     as pointed out by Daniel.
>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbdev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index 2a1724e..44c9ccc 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -63,8 +63,8 @@ static int intel_fbdev_set_par(struct fb_info *info)
>                  * now until we solve this for real.
>                  */
>                 mutex_lock(&fb_helper->dev->struct_mutex);
> -               ret = i915_gem_object_set_to_gtt_domain(ifbdev->fb->obj,
> -                                                       true);
> +               if (ifbdev->fb->obj)

I'm confused. Why are we doing this check now? If this is actually
needed, then the current set_to_gtt_domain() call will blow up too. So
this would be 2 different patches: one preventing the explosion, the
other doing obj_invalidate. Unless we don't need the obj check.

> +                       intel_fb_obj_invalidate(ifbdev->fb->obj, ORIGIN_GTT);
>                 mutex_unlock(&fb_helper->dev->struct_mutex);
>         }
>
> --
> 2.1.0
>
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-- 
Paulo Zanoni