diff mbox

[4.11] drm/i915: Do .init_clock_gating() earlier to avoid it clobbering watermarks

Message ID 20170315143158.31780-1-ville.syrjala@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ville Syrjälä March 15, 2017, 2:31 p.m. UTC
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Currently ILK-BDW explicitly disable LP1+ watermarks from their
.init_clock_gating() hooks. Unfortunately that hook gets called way too
late since by that time we've already initialized all the watermark
state tracking which then gets out of sync with the hardware state.

We may eventually want to consider killing off the explicit LP1+
disable from .init_clock_gating(). In the meantime however, we can
avoid the problem by reordering the init sequence such that
intel_modeset_init_hw()->intel_init_clock_gating() gets called
prior to the hardware state takeover.

I suppose prior to the two stage watermark programming we were
magically saved by something that forced the watermarks to be
reprogrammed fully after .init_clock_gating() got called. But
now that no longer happens.

Note that the diff might look a bit odd as it kills off one
call of intel_update_cdclk(), but that's fine because
intel_modeset_init_hw() does the exact same thing. Previously
we just did it twice.

Actually even this new init sequence is pretty bogus as
.init_clock_gating() really should be called before any gem
hardware init since it can  configure various clock gating
workarounds and whatnot that affect the GT side as well. Also
intel_modeset_init() really should get split up into better
defined init stages. Another "fun" detail is that
intel_modeset_gem_init() is where RPS/RC6 gets configured.
Why that is done from the display code is beyond me. I've
decided to leave all this be for now, and just try to fix
the init sequence enough for watermarks to work.

Cc: stable@vger.kernel.org
Cc: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: David Purton <dcpurton@marshwiggle.net>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reported-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-by: David Purton <dcpurton@marshwiggle.net>
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96645
Fixes: ed4a6a7ca853 ("drm/i915: Add two-stage ILK-style watermark programming (v11)")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170220140443.30891-1-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

Comments

Jani Nikula March 16, 2017, 8:06 a.m. UTC | #1
On Wed, 15 Mar 2017, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Currently ILK-BDW explicitly disable LP1+ watermarks from their
> .init_clock_gating() hooks. Unfortunately that hook gets called way too
> late since by that time we've already initialized all the watermark
> state tracking which then gets out of sync with the hardware state.
>
> We may eventually want to consider killing off the explicit LP1+
> disable from .init_clock_gating(). In the meantime however, we can
> avoid the problem by reordering the init sequence such that
> intel_modeset_init_hw()->intel_init_clock_gating() gets called
> prior to the hardware state takeover.
>
> I suppose prior to the two stage watermark programming we were
> magically saved by something that forced the watermarks to be
> reprogrammed fully after .init_clock_gating() got called. But
> now that no longer happens.
>
> Note that the diff might look a bit odd as it kills off one
> call of intel_update_cdclk(), but that's fine because
> intel_modeset_init_hw() does the exact same thing. Previously
> we just did it twice.
>
> Actually even this new init sequence is pretty bogus as
> .init_clock_gating() really should be called before any gem
> hardware init since it can  configure various clock gating
> workarounds and whatnot that affect the GT side as well. Also
> intel_modeset_init() really should get split up into better
> defined init stages. Another "fun" detail is that
> intel_modeset_gem_init() is where RPS/RC6 gets configured.
> Why that is done from the display code is beyond me. I've
> decided to leave all this be for now, and just try to fix
> the init sequence enough for watermarks to work.
>
> Cc: stable@vger.kernel.org
> Cc: Gabriele Mazzotta <gabriele.mzt@gmail.com>
> Cc: David Purton <dcpurton@marshwiggle.net>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Reported-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
> Reported-by: David Purton <dcpurton@marshwiggle.net>
> Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96645
> Fixes: ed4a6a7ca853 ("drm/i915: Add two-stage ILK-style watermark programming (v11)")
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Link: http://patchwork.freedesktop.org/patch/msgid/20170220140443.30891-1-ville.syrjala@linux.intel.com
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Thanks, pushed to drm-intel-fixes.

BR,
Jani.


> ---
>  drivers/gpu/drm/i915/intel_display.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 01341670738f..70be773b3e70 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -16696,12 +16696,11 @@ int intel_modeset_init(struct drm_device *dev)
>  		}
>  	}
>  
> -	intel_update_czclk(dev_priv);
> -	intel_update_cdclk(dev_priv);
> -	dev_priv->atomic_cdclk_freq = dev_priv->cdclk_freq;
> -
>  	intel_shared_dpll_init(dev);
>  
> +	intel_update_czclk(dev_priv);
> +	intel_modeset_init_hw(dev);
> +
>  	if (dev_priv->max_cdclk_freq == 0)
>  		intel_update_max_cdclk(dev_priv);
>  
> @@ -17258,8 +17257,6 @@ void intel_modeset_gem_init(struct drm_device *dev)
>  
>  	intel_init_gt_powersave(dev_priv);
>  
> -	intel_modeset_init_hw(dev);
> -
>  	intel_setup_overlay(dev_priv);
>  }
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 01341670738f..70be773b3e70 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -16696,12 +16696,11 @@  int intel_modeset_init(struct drm_device *dev)
 		}
 	}
 
-	intel_update_czclk(dev_priv);
-	intel_update_cdclk(dev_priv);
-	dev_priv->atomic_cdclk_freq = dev_priv->cdclk_freq;
-
 	intel_shared_dpll_init(dev);
 
+	intel_update_czclk(dev_priv);
+	intel_modeset_init_hw(dev);
+
 	if (dev_priv->max_cdclk_freq == 0)
 		intel_update_max_cdclk(dev_priv);
 
@@ -17258,8 +17257,6 @@  void intel_modeset_gem_init(struct drm_device *dev)
 
 	intel_init_gt_powersave(dev_priv);
 
-	intel_modeset_init_hw(dev);
-
 	intel_setup_overlay(dev_priv);
 }