[Intel-gfx] [PATCH] drm/i915: Transform WaInPlaceDecompressionHang to a simple reg write

[Chris Wilson]

Quoting Oscar Mateo (2017-09-06 22:27:47)
> 
> 
> On 09/06/2017 02:19 PM, Chris Wilson wrote:
> > Quoting Oscar Mateo (2017-09-06 22:12:11)
> >> Afaict, GEN9_GAMT_ECO_REG_RW_IA does not live in the context, so writing
> >> it on every context creation is overkill (and wrong).
> >>
> >> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> >> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> >> Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> >> ---
> >>   drivers/gpu/drm/i915/intel_engine_cs.c | 25 +++++++++++++++----------
> >>   1 file changed, 15 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> >> index 23812ec..9f01a5c 100644
> >> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> >> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> >> @@ -985,8 +985,9 @@ static int skl_init_workarounds(struct intel_engine_cs *engine)
> >>   
> >>          /* WaInPlaceDecompressionHang:skl */
> >>          if (IS_SKL_REVID(dev_priv, SKL_REVID_H0, REVID_FOREVER))
> >> -               WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
> >> -                          GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
> > Anything using a precalculated RMW value for a ctx register is indeed
> > fishy. Whilst you are checking this register, can you check whether the
> > other users of WA_SET_BIT/WA_CLR_BIT are indeed context bound?
> > -Chris
> 
> Sure, I'll try to go through all of them (but I'd like to clarify first 
> if I should also be moving those I find to xxx_init_clock_gating).

The short answer is probably not, init_clock_gating we expect to be
targetting display w/a. There's not always a clear divide between GT and
display, but we keep on muttering that we should keep them them as
cleanly separated as possible so that we know where to look when
different IP blocks are updated. (And yes the name is one of those
things that we keep on waiting for someone else to fix.)
-Chris