Re: [PATCH] drm/i915: Fix ilk watermarks calculation when primary plane is disabled

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 20 May 2015, Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> wrote:
> On Fedora 21 or 22, when the transition from the X server to the wayland
> compositor is done, the CRTC with the login screen is left active with a
> disabled fb. A cursor ioctl after the transition causes the watermarks
> to be updated, but due to the logic in intel_crtc_active() checking for
> the primary plane fb, the update considers all planes to be disabled,
> untimately setting the wrong watermark values and causing screen
> flicker. Since the crtc is active, a modeset done later is skipped and
> replaced with a flip, which doesn't update the watermarks.
>
> This regression was introduced somewhere between v3.16 and v3.17.
> Another issue prevented me from doing a full bisect, but the issue was
> introduced in one of the following skipped commits:
>
>     commit 7707e6535f43328e05e4729ac96eee864b90e8a4
>     Author: Rob Clark <robdclark@gmail.com>
>     Date:   Thu Jul 17 23:30:04 2014 -0400
>
>         drm/i915: use helpers
>
>     commit ca5a1b9ba0fb5291b555a23b76dbe5f6c30bfd7a
>     Merge: c7dbc6c 3488229
>     Author: Dave Airlie <airlied@redhat.com>
>     Date:   Wed Jul 9 10:38:42 2014 +1000
>
>         Merge tag 'drm-intel-next-2014-06-20' of git://anongit.freedesktop.org/drm-intel into drm-next
>
>     commit c51f71679042a5f388d9580ffbede14c897f1e86
>     Merge: b957f45 7b3c29f
>     Author: Dave Airlie <airlied@redhat.com>
>     Date:   Sat Jul 19 16:43:41 2014 +1000
>
>         Merge tag 'drm-intel-next-2014-07-11' of git://anongit.freedesktop.org/drm-intel into drm-next
>
> This patch is a simplified version of the following commits:
>
>     commit 3dd512fbda0d87d1c3fb44bf878b262baee98fb6
>     Author: Matt Roper <matthew.d.roper@intel.com>
>     Date:   Fri Feb 27 10:12:00 2015 -0800
>
>         drm/i915: Kill intel_crtc->cursor_{width, height} (v2)
>
>     commit 54da691deb123c045259ebf4f5c67381244f58f1
>     Author: Thomas Gummerer <t.gummerer@gmail.com>
>     Date:   Thu May 14 09:16:39 2015 +0200
>
>         drm/i915: fix screen flickering

This is expected to land in v4.1-rc5, i.e. these are all upstream
commits. And I assume none of them apply to stable kernels directly.

>
>     commit 3ef00284e6a48f7deb0784ccca0478ebb7d4bcfc
>     Author: Matt Roper <matthew.d.roper@intel.com>
>     Date:   Mon Mar 9 10:19:24 2015 -0700
>
>         drm/i915: Use crtc->state->active in ilk/skl watermark calculations (v3)
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90508
> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1218688
> Cc: stable@vger.kernel.org

I (and most likely the stable team) would like to know which stable
kernel versions this is targeting.

Do you have Tested-bys against the stable versions you're targeting?

Anyway this is

Acked-by: Jani Nikula <jani.nikula@intel.com>


BR,
Jani.

> Cc: Dave Airlie <airlied@gmail.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 24d77dd..3d67f8e 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -1898,16 +1898,24 @@ static void ilk_compute_wm_parameters(struct drm_crtc *crtc,
>  	enum pipe pipe = intel_crtc->pipe;
>  	struct drm_plane *plane;
>  
> -	if (!intel_crtc_active(crtc))
> +	if (!intel_crtc->active)
>  		return;
>  
>  	p->active = true;
>  	p->pipe_htotal = intel_crtc->config->base.adjusted_mode.crtc_htotal;
>  	p->pixel_rate = ilk_pipe_pixel_rate(dev, crtc);
> -	p->pri.bytes_per_pixel = crtc->primary->fb->bits_per_pixel / 8;
> +
> +
> +	if (crtc->primary->fb)
> +		p->pri.bytes_per_pixel = crtc->primary->fb->bits_per_pixel / 8;
> +	else
> +		p->pri.bytes_per_pixel = 4;
> +
>  	p->cur.bytes_per_pixel = 4;
> +
>  	p->pri.horiz_pixels = intel_crtc->config->pipe_src_w;
> -	p->cur.horiz_pixels = intel_crtc->cursor_width;
> +	p->cur.horiz_pixels = intel_crtc->base.cursor->state->crtc_w;
> +
>  	/* TODO: for now, assume primary and cursor planes are always enabled. */
>  	p->pri.enabled = true;
>  	p->cur.enabled = true;
> -- 
> 2.1.0
>

-- 
Jani Nikula, Intel Open Source Technology Center