On Wed, Sep 27, 2017 at 09:08:10PM +0000, Oscar Mateo wrote: > > > On 09/27/2017 02:01 PM, Rodrigo Vivi wrote: > > On CNL, HDC_CHICKEN0 "is write-only from LRI command. > > However, it is readable for context save." > > > > So we have no ways to check the coherency by reading it back on > > our tests. > > > > So let's just write that bit directly without saving it to > > dev_priv->workarounds. > > Wait, it's not that simple: CNL_HDC_CHICKEN0 lives in the context image, so > you are going to revert the value as soon as you restore the next context > (you want to save it in dev_priv->workarounds so that > intel_ring_workarounds_emit applies it to every newly created context).
hm... that makes sense... I was only with the WA description in my head that states to set only once at boot: " To avoid a potential hang condition with TLB invalidation driver should enable masked bit 5 of MMIO 0xE5F0 at boot." But apparently just a bad description in spec, right?! If this is the case probably dev_priv->workarouds will need another component "permission" to handle write-only registers and avoid reading that on debugfs? Or any thing smarter? > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102943 > > Fixes: acfb5554c769 ("drm/i915/cnl: WaForceContextSaveRestoreNonCoherent") > > Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com> > > Cc: Oscar Mateo <oscar.ma...@intel.com> > > Cc: Chris Wilson <ch...@chris-wilson.co.uk> > > Signed-off-by: Rodrigo Vivi <rodrigo.v...@intel.com> > > --- > > drivers/gpu/drm/i915/intel_engine_cs.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c > > b/drivers/gpu/drm/i915/intel_engine_cs.c > > index a28e2a864cf1..047ba0a0308d 100644 > > --- a/drivers/gpu/drm/i915/intel_engine_cs.c > > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c > > @@ -1251,8 +1251,8 @@ static int cnl_init_workarounds(struct > > intel_engine_cs *engine) > > GAMT_CHKN_DISABLE_I2M_CYCLE_ON_WR_PORT)); > > /* WaForceContextSaveRestoreNonCoherent:cnl */ > > - WA_SET_BIT_MASKED(CNL_HDC_CHICKEN0, > > - HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT); > > + I915_WRITE(CNL_HDC_CHICKEN0, > > + > > _MASKED_BIT_ENABLE(HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT)); > > /* WaThrottleEUPerfToAvoidTDBackPressure:cnl(pre-prod) */ > > if (IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0)) > _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
