Re: [PATCH] drm/i915/chv: Implement WaDisableShadowRegForCpd

Ville Syrjälä
2015-04-14T10:59:57Z

On Tue, Apr 14, 2015 at 03:58:54PM +0530, deepak.s@linux.intel.com wrote:
> From: Deepak S <deepak.s@linux.intel.com>
>
> This WA disable usage of shadow register during CPD/RC6 transactions on
> CHV

I suppose is a workaround for the shadow vs. wake FIFO problem... Yeah
hsd seems to agree (after a bit of extra digging).

>
> Signed-off-by: Deepak S <deepak.s@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> 2 files changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 9c97842..bcdb16b 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6206,6 +6206,7 @@ enum skl_disp_power_wells {
> #define GTFIFOCTL 0x120008
> #define GT_FIFO_FREE_ENTRIES_MASK 0x7f
> #define GT_FIFO_NUM_RESERVED_ENTRIES 20
> +#define GT_FIFO_CTL_BLOCK_POLICY (3<<11)

GT_FIFO_CTL_BLOCK_ALL_POLICY_STALL (1 << 12)
GT_FIFO_CTL_RC6_POLICY_STALL (1 << 11)

perhaps?

>
> #define HSW_IDICR 0x9008
> #define IDIHASHMSK(x) (((x) & 0x3f) << 16)
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 4dd8b41..b9d3c00 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -6431,6 +6431,10 @@ static void cherryview_init_clock_gating(struct drm_device *dev)
> /* WaDisableSDEUnitClockGating:chv */
> I915_WRITE(GEN8_UCGCTL6, I915_READ(GEN8_UCGCTL6) |
> GEN8_SDEUNIT_CLOCK_GATE_DISABLE);
> +
> + /* WaDisableShadowRegForCpd */
> + I915_WRITE(GTFIFOCTL, I915_READ(GTFIFOCTL) |
> + GT_FIFO_CTL_BLOCK_POLICY);

I think __intel_uncore_early_sanitize() might be a better place for
this.

> }
>
> static void g4x_init_clock_gating(struct drm_device *dev)
> --
> 1.9.1

--
Ville Syrjälä
Intel OTC