[PATCH 1/2] drm/xe: fix WA 14018094691

[Matt Roper]

On Wed, Aug 07, 2024 at 04:51:32PM -0500, Lucas De Marchi wrote:
> On Wed, Aug 07, 2024 at 02:11:05PM GMT, Daniele Ceraolo Spurio wrote:
> > This WA is applied while initializing the media GT, but it is currently
> > defined as a primary GT WA (because it modifies a register on the
> > primary GT), so the XE_WA macro is returning false even when the WA
> > should be applied.
> 
> humn... I don't see the media gt marked in the WA db. Does it need to
> be updated considering the GSC is actually loaded in the media GT? But
> it would be odd to write to the primary_gt. So... alternative approach
> that I think would be more correct would be to change the implementation
> in drivers/gpu/drm/xe/xe_gsc.c so it passes the primary_gt to XE_WA(),
> just like it's doing when writing the register.
> 
> Thoughts? Would also like to see Matt Roper's opinion

Yeah, I agree.  It sounds like the workaround applicability is keyed off
the primary GT's IP and the registers that need to be written are also
the primary GT's copy, so I think we should just be passing that GT to
XE_WA() as well.

BTW, it looks like this workaround needs to apply to both graphics
version 20.04 (used by LNL) and 20.01 (used by BMG) if I'm reading
correctly?


Matt

> 
> Lucas De Marchi
> 
> > Since both GTs are involved in the flow, fix this by marking the WA as
> > applying to the platform instead of just the specific GT.
> > 
> > Note that this WA only applies to PXP and we don't yet support that in
> > Xe, so there are no negative effects to this bug, which is why we didn't
> > see any errors in testing.
> > 
> > Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Cc: Matt Roper <matthew.d.roper at intel.com>
> > ---
> > drivers/gpu/drm/xe/xe_wa_oob.rules | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_wa_oob.rules b/drivers/gpu/drm/xe/xe_wa_oob.rules
> > index 540d38603f32..40354fb01737 100644
> > --- a/drivers/gpu/drm/xe/xe_wa_oob.rules
> > +++ b/drivers/gpu/drm/xe/xe_wa_oob.rules
> > @@ -19,7 +19,7 @@
> > 		GRAPHICS_VERSION_RANGE(1270, 1274)
> > 		MEDIA_VERSION(1300)
> > 		PLATFORM(DG2)
> > -14018094691	GRAPHICS_VERSION(2004)
> > +14018094691	PLATFORM(LUNARLAKE)
> > 14019882105	GRAPHICS_VERSION(2004), GRAPHICS_STEP(A0, B0)
> > 18024947630	GRAPHICS_VERSION(2001)
> > 		GRAPHICS_VERSION(2004)
> > -- 
> > 2.43.0
> > 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation