Re: [PATCH 1/4] drm/i915/bxt: limit WaDisableMaskBasedCammingInRCC to stepping A

[Imre Deak <imre.deak@intel.com>]

On ti, 2015-05-19 at 15:46 +0100, Damien Lespiau wrote:
> On Tue, May 19, 2015 at 03:39:25PM +0100, Damien Lespiau wrote:
> > On Tue, May 19, 2015 at 03:04:59PM +0300, Imre Deak wrote:
> > > Also make the WA comment consistent with the rest, where the stepping
> > > info is not shown.
> > > 
> > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_ringbuffer.c | 9 +++------
> > >  1 file changed, 3 insertions(+), 6 deletions(-)
> > > 
> > > [ The patchset is a follow-up to:
> > >   http://lists.freedesktop.org/archives/intel-gfx/2015-May/065989.html ]
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > > index 9b96ed7..461b9be 100644
> > > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > > @@ -961,12 +961,9 @@ static int gen9_init_workarounds(struct intel_engine_cs *ring)
> > >  	WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
> > >  			  GEN9_CCS_TLB_PREFETCH_ENABLE);
> > >  
> > > -	/*
> > > -	 * FIXME: don't apply the following on BXT for stepping C. On BXT A0
> > > -	 * the flag reads back as 0.
> > > -	 */
> > > -	/* WaDisableMaskBasedCammingInRCC:sklC,bxtA */
> > > -	if (INTEL_REVID(dev) == SKL_REVID_C0 || IS_BROXTON(dev))
> > > +	/* WaDisableMaskBasedCammingInRCC:skl,bxt */
> > 
> > For the record, there seem to be some confusion in the W/A db:
> > 
> >   - The W/A seems to have been renamed to WaDisablePixelMaskBasedCammingInRcpbe
> >     and indeed there's a bit to do that, but the bug in question talks
> >     about bit 14 of 7308, which is the disabling bit for the RCC unit
> >   - The W/A isn't listed in the W/A db for BXT
> > 
> > In doubt, defaulting to trusting the spec and bug db is probably the
> > saner option, so:
> > 
> > Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
> 
> Spoke too soon. This register is in the render context so has to be
> written from the ring...

Not sure what you mean. I thought all WAs inited here are written from
the ring.

--Imre


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