On Sat, Nov 11, 2017 at 10:03:36AM +0000, Chris Wilson wrote:
> gem_workarounds reports that the SLICE_UNIT_LEVEL_CLKGATE write isn't
> sticking. Commit 0a60797a0efb ("drm/i915: Implement
> ReadHitWriteOnlyDisable.") presumes that SLICE_UNIT_LEVEL_CLKGATE is a
> masked register in the context image, but commit 90007bca6162
> ("drm/i915/cnl: Introduce initial Cannonlake Workarounds.") lists it as
> an ordering unmasked register. The masked write will be losing the
> default settings if we trust the original commit. That gem_workarounds
> reports the value is lost entirely is more worrying though -- but it
> clearly suggests that it is not a masked register in the context image,
> so unify both w/a to use the original rmw.
Thanks for fixing this.
Reviewed-by: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
> Fixes: 0a60797a0efb ("drm/i915: Implement ReadHitWriteOnlyDisable.")
> References: 90007bca6162 ("drm/i915/cnl: Introduce initial Cannonlake Workarounds.")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_engine_cs.c | 3 ---
> drivers/gpu/drm/i915/intel_pm.c | 8 +++++---
> 2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index 23694916662f..125e4d90c5f7 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1324,9 +1324,6 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
> WA_SET_FIELD_MASKED(GEN8_CS_CHICKEN1, GEN9_PREEMPT_GPGPU_LEVEL_MASK,
> GEN9_PREEMPT_GPGPU_COMMAND_LEVEL);
>
> - /* ReadHitWriteOnlyDisable: cnl */
> - WA_SET_BIT_MASKED(SLICE_UNIT_LEVEL_CLKGATE, RCCUNIT_CLKGATE_DIS);
> -
> /* WaEnablePreemptionGranularityControlByUMD:cnl */
> I915_WRITE(GEN7_FF_SLICE_CS_CHICKEN1,
> _MASKED_BIT_ENABLE(GEN9_FFSC_PERCTX_PREEMPT_CTRL));
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index c1a56809f143..6dee6b15f726 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -8474,11 +8474,13 @@ static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
> I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
> DISP_FBC_MEMORY_WAKE);
>
> + val = I915_READ(SLICE_UNIT_LEVEL_CLKGATE);
> + /* ReadHitWriteOnlyDisable:cnl */
> + val |= RCCUNIT_CLKGATE_DIS;
> /* WaSarbUnitClockGatingDisable:cnl (pre-prod) */
> if (IS_CNL_REVID(dev_priv, CNL_REVID_A0, CNL_REVID_B0))
> - I915_WRITE(SLICE_UNIT_LEVEL_CLKGATE,
> - I915_READ(SLICE_UNIT_LEVEL_CLKGATE) |
> - SARBUNIT_CLKGATE_DIS);
> + val |= SARBUNIT_CLKGATE_DIS;
> + I915_WRITE(SLICE_UNIT_LEVEL_CLKGATE, val);
>
> /* Display WA #1133: WaFbcSkipSegments:cnl */
> val = I915_READ(ILK_DPFC_CHICKEN);
> --
> 2.15.0
>
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