[Intel-gfx] [PATCH 4/4] drm/i915: Restrict SNB LP3+ disable to Thinkpad X220 tablet

[Ville Syrjälä]

On Mon, Feb 25, 2019 at 05:45:38PM +0200, Ville Syrjälä wrote:
> On Fri, Feb 22, 2019 at 05:52:51PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > The only machine we know for sure to require the LP3+ disable
> > is the Lenovo Thinkpad X220 tablet. Originally in commit
> > 03981c6ebec4 ("drm/i915: Disable LP3 watermarks on all SNB
> > machines") I disabled LP3+ watermarks on all SNB machines,
> > partially for safety, and partially since I didn't want to
> > add a quirk. But since we now have another watermark quirk
> > anyway let's reduce the SNB LP3+ disable scope to the x220
> > tablet only.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 2a4b5014f56e..b225461455c2 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -3038,7 +3038,7 @@ static void ilk_wm_disable_quirk(struct drm_i915_private *dev_priv,
> >  	intel_print_wm_latency(dev_priv, "Cursor", dev_priv->wm.cur_latency);
> >  }
> >  
> > -static void snb_wm_lp3_irq_quirk(struct drm_i915_private *dev_priv)
> > +static void ilk_wm_disable_lp3(struct drm_i915_private *dev_priv)
> >  {
> >  	/*
> >  	 * On some SNB machines (Thinkpad X220 Tablet at least)
> > @@ -3060,6 +3060,11 @@ static void ilk_wm_disable_lp1_quirk(struct drm_i915_private *dev_priv)
> >  }
> >  
> >  static const struct intel_pci_quirk ilk_wm_quirks[] = {
> > +	/*
> > +	 * Lenovo ThinkPad X220 Tablet (snb)
> > +	 * CPU doesn't wake up for vblank interrupts with LP3.
> > +	 */
> > +	{ 0x0126, 0x17aa, 0x21db, ilk_wm_disable_lp3 },
> 
> Hmm. Somehow I had convinced myself that this would also cover the second
> bugreport (https://bugs.freedesktop.org/show_bug.cgi?id=101269) we had
> about this. But looks like we'd need another quirk entry here for that
> machine (a Thinkpad T420). I'll respin with. *hopefully* there aren't
> many more.

https://bugs.freedesktop.org/show_bug.cgi?id=104573#c5 suggests that a
Lifeboot T901 is also affected. I guess I'll just have to drop my
plans to reduce the scope of this quirk :(

> 
> >  	/*
> >  	 * Lenovo Thinkpad T431s (ivb)
> >  	 * Massive underruns with LP1+.
> > @@ -3084,10 +3089,8 @@ static void ilk_setup_wm_latency(struct drm_i915_private *dev_priv)
> >  	intel_print_wm_latency(dev_priv, "Sprite", dev_priv->wm.spr_latency);
> >  	intel_print_wm_latency(dev_priv, "Cursor", dev_priv->wm.cur_latency);
> >  
> > -	if (IS_GEN(dev_priv, 6)) {
> > +	if (IS_GEN(dev_priv, 6))
> >  		snb_wm_latency_quirk(dev_priv);
> > -		snb_wm_lp3_irq_quirk(dev_priv);
> > -	}
> >  
> >  	intel_apply_pci_quirks(dev_priv, ilk_wm_quirks);
> >  }
> > -- 
> > 2.19.2
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Ville Syrjälä
Intel