Re: [PATCH v2] drm/i915:bxt: implement WaProgramL3SqcReg1DefaultForPerf

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

On Wed, Apr 20, 2016 at 07:19:32PM +0100, Chris Wilson wrote:
> On Wed, Apr 20, 2016 at 03:51:49PM +0000, Gore, Tim wrote:
> > 
> > Tim Gore 
> > Intel Corporation (UK) Ltd. - Co. Reg. #1134945 - Pipers Way, Swindon SN3 1RJ
> > 
> > 
> > > -----Original Message-----
> > > From: Thierry, Michel
> > > Sent: Wednesday, April 20, 2016 4:00 PM
> > > To: Gore, Tim; intel-gfx@lists.freedesktop.org
> > > Subject: Re: [PATCH v2] drm/i915:bxt: implement
> > > WaProgramL3SqcReg1DefaultForPerf
> > > 
> > > On 4/20/2016 3:23 PM, tim.gore@intel.com wrote:
> > > > From: Tim Gore <tim.gore@intel.com>
> > > >
> > > > This patch applies a performance enhancement workaround based on
> > > > analysis of DX and OCL S-Curve workloads.
> > > >
> > > > v2: Only apply to B0 onwards
> > > >
> > > > Signed-off-by: Tim Gore <tim.gore@intel.com>
> > > > ---
> > > >   drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > >   drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > >   2 files changed, 5 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > > > b/drivers/gpu/drm/i915/i915_reg.h index f0a6d85..13e154a 100644
> > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > @@ -6074,6 +6074,7 @@ enum skl_disp_power_wells {
> > > >
> > > >   #define GEN8_L3SQCREG1				_MMIO(0xB100)
> > > >   #define  BDW_WA_L3SQCREG1_DEFAULT		0x784000
> > > > +#define  BXT_WA_L3SQCREG1_DEFAULT		0xF84000
> > > >
> > > >   #define GEN7_L3CNTLREG1				_MMIO(0xB01C)
> > > >   #define  GEN7_WA_FOR_GEN7_L3_CONTROL
> > > 	0x3C47FF8C
> > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c
> > > > b/drivers/gpu/drm/i915/intel_pm.c index b7c2186..eecdc3a6 100644
> > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > @@ -76,6 +76,10 @@ static void bxt_init_clock_gating(struct drm_device
> > > *dev)
> > > >   	if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER))
> > > >   		I915_WRITE(GEN9_CLKGATE_DIS_0,
> > > I915_READ(GEN9_CLKGATE_DIS_0) |
> > > >   			   PWM1_GATING_DIS | PWM2_GATING_DIS);
> > > > +
> > > > +	/* WaProgramL3SqcReg1DefaultForPerf:bxt */
> > > > +	if (IS_BXT_REVID(dev, BXT_REVID_B0, REVID_FOREVER))
> > > > +		I915_WRITE(GEN8_L3SQCREG1,
> > > BXT_WA_L3SQCREG1_DEFAULT);
> > > >   }
> > > >
> > > >   static void i915_pineview_get_mem_freq(struct drm_device *dev)
> > > >
> > > 
> > > Isnt it better to add this to bxt_init_workarounds() instead of
> > > bxt_init_clock_gating()?
> > 
> > There is an equivalent Wa for bdw in bdw_init_clock_gating, so I just tried to
> > stay consistent with that. I'm not sure if this W/a will persist across
> > suspend/resume. bxt_init_workarounds only gets called after reset, not
> > on resume as far as I know. I'll investigate further
> 
> init_clock_gating() is called on init/reset/resume. Use it to set global
> registers. (Once upon a time it did only setup the clock gatings...)

It's not called on reset. Or at least that was the case last time I
looked. Which is a rather big problem. My old idea was that we'd move
anything that gets clobbered by a GPU reset out from init_clock_gating
into some more suitable place that does get called on reset.

-- 
Ville Syrjälä
Intel OTC
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