Re: [Intel-gfx] [PATCH] drm/i915/tgl: Implement Wa_1606931601

From: Matt Roper <matthew.d.roper@intel.com>
To: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] drm/i915/tgl: Implement Wa_1606931601
Date: Thu, 23 Jan 2020 09:50:12 -0800	[thread overview]
Message-ID: <20200123175012.GI2244136@mdroper-desk1.amr.corp.intel.com> (raw)
In-Reply-To: <20200122234027.9373-1-anusha.srivatsa@intel.com>

On Wed, Jan 22, 2020 at 03:40:27PM -0800, Anusha Srivatsa wrote:
> Disable Early Read and Src Swap by setting the bit 14
> and 15 in the chicken register.
> 
> BSpec: 46045,52890
> HSDES: 1606931601

Hmm.  The bspec WA description (which is very poorly written) only
mentions setting bit 14, but comments in the HSD indicate that both 14
and 15 should be set.  Do we have offline confirmation/clarification
about which we should trust?

If we do need to program both bits, it might still be a good idea to use
two separate #define's for those rather than a single bitmask to make it
more clear what we're doing and also to give us the option of just
setting one or the other in case that winds up being necessary as a
workaround for a different platform or future stepping.

Matt

> 
> Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 5 +++++
>  drivers/gpu/drm/i915/i915_reg.h             | 1 +
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 5a7db279f702..53b448b61a5f 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -593,6 +593,11 @@ static void tgl_ctx_workarounds_init(struct intel_engine_cs *engine,
>  	wa_add(wal, FF_MODE2, FF_MODE2_TDS_TIMER_MASK, val,
>  	       IS_TGL_REVID(engine->i915, TGL_REVID_A0, TGL_REVID_A0) ? 0 :
>  			    FF_MODE2_TDS_TIMER_MASK);
> +
> +	/* Wa_1606931601:tgl */
> +	WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
> +			  GEN11_EARLY_READ_SRC0_DISABLE_MASK);
> +
>  }
>  
>  static void
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index b93c4c18f05c..69a1c2227b91 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9146,6 +9146,7 @@ enum {
>  #define   DOP_CLOCK_GATING_DISABLE	(1 << 0)
>  #define   PUSH_CONSTANT_DEREF_DISABLE	(1 << 8)
>  #define   GEN11_TDL_CLOCK_GATING_FIX_DISABLE	(1 << 1)
> +#define   GEN11_EARLY_READ_SRC0_DISABLE_MASK	REG_GENMASK(15, 14)
>  
>  #define HSW_ROW_CHICKEN3		_MMIO(0xe49c)
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> -- 
> 2.23.0
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795
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