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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Feb 22, 2019 at 05:52:51PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@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@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.

>  	/*
>  	 * 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
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