Hi Matt,
> > +static void intel_gt_apply_ccs_mode(struct intel_gt *gt)
> > +{
> > + u32 mode;
> > + int cslice;
> > +
> > + if (!IS_DG2(gt->i915))
> > + return;
> > +
> > + /* Set '0' as a default CCS id to all the cslices */
> > + mode = 0;
> > +
> > + for (cslice = 0; cslice < hweight32(CCS_MASK(gt)); cslice++)
> > + /* Write 0x7 if no CCS context dispatches to this cslice */
> > + if (!(CCS_MASK(gt) & BIT(cslice)))
> > + mode |= XEHP_CCS_MODE_CSLICE(cslice,
> > + XEHP_CCS_MODE_CSLICE_MASK);
> > +
> > + intel_uncore_write(gt->uncore, XEHP_CCS_MODE, mode);
>
> This is still going to hook all available cslices up to hardware engine
> ccs0. But what you actually want is to hook them all up to what
> userspace sees as CCS0 (i.e., the first CCS engine that wasn't fused
> off). Hardware's engine numbering and userspace's numbering aren't the
> same.
Yes, correct... we had so many discussions and I forgot about it :-)
> Also, if you have a part that only has hardware ccs1/cslice1 for
> example, you're not going to set cslices 2 & 3 to 0x7 properly.
Good point also here, the XEHP_CCS_MODE register is indeed
generic to all platforms.
> So probably what you want is something like this (untested):
>
> static void intel_gt_apply_ccs_mode(struct intel_gt *gt)
> {
> u32 mode = 0;
> int first_ccs = __ffs(CCS_MASK(gt));
>
> /*
> * Re-assign every present cslice to the first available CCS
> * engine; mark unavailable cslices as unused.
> */
> for (int cslice = 0; cslice < 4; cslice++) {
> if (CCS_MASK(gt) & BIT(cslice))
> mode |= XEHP_CCS_MODE_CSLICE(cslice, first_ccs);
> else
> mode |= XEHP_CCS_MODE_CSLICE(cslice,
> XEHP_CCS_MODE_CSLICE_MASK);
> }
>
> intel_uncore_write(gt->uncore, XEHP_CCS_MODE, mode);
> }
>
> > +}
> > +
> > int intel_gt_init_hw(struct intel_gt *gt)
> > {
> > struct drm_i915_private *i915 = gt->i915;
> > @@ -195,6 +215,9 @@ int intel_gt_init_hw(struct intel_gt *gt)
> >
> > intel_gt_init_swizzling(gt);
> >
> > + /* Configure CCS mode */
> > + intel_gt_apply_ccs_mode(gt);
>
> This is only setting this once during init. The value gets lost on
> every RCS/CCS reset, so we need to make sure it gets reapplied when
> necessary. That means you either need to add this to the GuC regset, or
> you need to implement the programming as a "fake workaround" so that the
> workaround framework will take care of the re-application for you.
OK, I'll hook everything up in the ccs_engine_wa_init().
Thanks,
Andi
