On Sun, Feb 12, 2017 at 01:32:52PM +0000, Robert Bragg wrote:
> This workaround for BDW was incomplete as it also requires EUTC clock
> gating to be disabled via UCGCTL1.
> 
> v2: read modify write UCGTL1 in broadwell_init_clock_gating (Ville)
> 
> Signed-off-by: Robert Bragg <rob...@sixbynine.org>
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>

Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com>

Do we know if this fixes something real? And if so, do we want cc:stable?

> ---
>  drivers/gpu/drm/i915/intel_pm.c         | 8 ++++++++
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 6 +++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index c0b0f5a4b9f1..3c13be8985f1 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -7229,6 +7229,14 @@ static void broadwell_init_clock_gating(struct 
> drm_i915_private *dev_priv)
>                  | KVM_CONFIG_CHANGE_NOTIFICATION_SELECT);
>  
>       lpt_init_clock_gating(dev_priv);
> +
> +     /* WaDisableDopClockGating:bdw
> +      *
> +      * Also see the CHICKEN2 write in bdw_init_workarounds() to disable DOP
> +      * clock gating.
> +      */
> +     I915_WRITE(GEN6_UCGCTL1,
> +                I915_READ(GEN6_UCGCTL1) | GEN6_EU_TCUNIT_CLOCK_GATE_DISABLE);
>  }
>  
>  static void haswell_init_clock_gating(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c 
> b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index d3d1e64f2498..d93d5f8f02d8 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -825,7 +825,11 @@ static int bdw_init_workarounds(struct intel_engine_cs 
> *engine)
>       /* WaDisableThreadStallDopClockGating:bdw (pre-production) */
>       WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);
>  
> -     /* WaDisableDopClockGating:bdw */
> +     /* WaDisableDopClockGating:bdw
> +      *
> +      * Also see the related UCGTCL1 write in broadwell_init_clock_gating()
> +      * to disable EUTC clock gating.
> +      */
>       WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
>                         DOP_CLOCK_GATING_DISABLE);
>  
> -- 
> 2.11.1

-- 
Ville Syrjälä
Intel OTC
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