[Intel-gfx] [PATCH 2/2] drm/i915/tgl: Skip Wa_1604555607 verification at A0

[Chris Wilson]

Quoting Ramalingam C (2019-10-01 18:26:24)
> Read of FF_MODE2 register is broken at TGL A0. Hence verification of the
> Wa_1604555607 associated to that register needs to be skipped.
> 
> Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 22 ++++++++++++++++++++-
>  drivers/gpu/drm/i915/i915_drv.h             |  6 ++++++
>  2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 4049b876492a..c63d8c3df4d3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -991,10 +991,21 @@ wa_list_apply(struct intel_uncore *uncore, const struct i915_wa_list *wal)
>  
>         for (i = 0, wa = wal->list; i < wal->count; i++, wa++) {
>                 intel_uncore_rmw_fw(uncore, wa->reg, wa->mask, wa->val);
> -               if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
> +               if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)) {
> +
> +                       /*
> +                        * Read of FF_MODE2 is broken on TGL A0.
> +                        * Hence skip the corresponding WA verification.
> +                        */
> +                       if (IS_TGL_REVID(uncore->i915, 0, TGL_REVID_A0) &&
> +                           i915_mmio_reg_equal(wa->reg, FF_MODE2) &&
> +                           wa->mask == FF_MODE2_TDS_TIMER_MASK)
> +                               continue;

This does not scale very well. You will note that wa_verify() already
includes a detail on which bits can be read back from HW.
-Chris