[Intel-gfx] [PATCH 09/24] drm/i915: Keep vblank interrupts enabled while enabling/disabling planes

[Paulo Zanoni]

2014-03-07 13:32 GMT-03:00  <ville.syrjala at linux.intel.com>:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> We may have use for vblank interrupts during plane enabling/disabling, so
> don't call drm_vblank_off() until planes are off, and call
> drm_vblank_on() just before we start to enable the planes.

Just like the previous patch, this one also needs a more precise
description of the reasons and consequences. If this is going to be
needed in the future, it is probably a good idea to briefly describe
why and the use case you are planning. Because if, in the future, we
ever bisect a bug to this patch, and need to revert, we won't know if
the revert breaks some other feature.

>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 4986887..c028b5c 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3545,6 +3545,8 @@ static void ilk_crtc_enable_planes(struct drm_crtc *crtc)
>         int pipe = intel_crtc->pipe;
>         int plane = intel_crtc->plane;
>
> +       drm_vblank_on(dev, pipe);
> +
>         intel_enable_primary_plane(dev_priv, plane, pipe);
>         intel_enable_planes(crtc);
>         intel_crtc_update_cursor(crtc, true);
> @@ -3555,8 +3557,6 @@ static void ilk_crtc_enable_planes(struct drm_crtc *crtc)
>         mutex_lock(&dev->struct_mutex);
>         intel_update_fbc(dev);
>         mutex_unlock(&dev->struct_mutex);
> -
> -       drm_vblank_on(dev, pipe);
>  }
>
>  static void ilk_crtc_disable_planes(struct drm_crtc *crtc)
> @@ -3568,7 +3568,6 @@ static void ilk_crtc_disable_planes(struct drm_crtc *crtc)
>         int plane = intel_crtc->plane;
>
>         intel_crtc_wait_for_pending_flips(crtc);
> -       drm_vblank_off(dev, pipe);
>
>         if (dev_priv->fbc.plane == plane)
>                 intel_disable_fbc(dev);
> @@ -3579,6 +3578,8 @@ static void ilk_crtc_disable_planes(struct drm_crtc *crtc)
>         intel_disable_planes(crtc);
>         intel_disable_primary_plane(dev_priv, plane, pipe);
>         intel_wait_for_vblank(dev, pipe);
> +
> +       drm_vblank_off(dev, pipe);
>  }
>
>  static void ironlake_crtc_enable(struct drm_crtc *crtc)
> --
> 1.8.3.2
>
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-- 
Paulo Zanoni