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).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102943
Fixes: acfb5554c769 ("drm/i915/cnl: WaForceContextSaveRestoreNonCoherent")
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
---
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))
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