[Intel-gfx] [PATCH] drm/i915/gt/tgl: implement Wa_1409085225

[Rafael Antognolli]

On Tue, Feb 18, 2020 at 02:47:10PM -0500, Matt Atwood wrote:
> Disable Push Constant buffer addition for A0, which can cause FIFO
> underruns.
> 
> Fix a minor white space issue while we're here.
> 
> Bspec: 52890
> Cc: Rafael Antognolli <rafael.antognolli at intel.com>
> Signed-off-by: Matt Atwood <matthew.s.atwood at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 10 ++++++++++
>  drivers/gpu/drm/i915/i915_reg.h             |  3 +++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 887e0dc701f7..9bbd28aa9bde 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -580,6 +580,7 @@ static void icl_ctx_workarounds_init(struct intel_engine_cs *engine,
>  static void tgl_ctx_workarounds_init(struct intel_engine_cs *engine,
>  				     struct i915_wa_list *wal)
>  {
> +	struct drm_i915_private *i915 = engine->i915;
>  	u32 val;
>  
>  	/* Wa_1409142259:tgl */
> @@ -590,6 +591,7 @@ static void tgl_ctx_workarounds_init(struct intel_engine_cs *engine,
>  	val = intel_uncore_read(engine->uncore, FF_MODE2);
>  	val &= ~FF_MODE2_TDS_TIMER_MASK;
>  	val |= FF_MODE2_TDS_TIMER_128;
> +
>  	/*
>  	 * FIXME: FF_MODE2 register is not readable till TGL B0. We can
>  	 * enable verification of WA from the later steppings, which enables
> @@ -598,6 +600,14 @@ 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_1409085225:tgl
> +	 *
> +	 * Push Constant Buffer can case FIFO underruns on A0
> +	 */
> +	if (IS_TGL_REVID(i915, TGL_REVID_A0, TGL_REVID_A0))

Is this really only applicable to A stepping?

> +		WA_SET_BIT_MASKED(GEN9_ROW_CHICKEN4,
> +				  GEN12_DISABLE_TDL_PUSH);
>  }
>  
>  static void
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index b09c1d6dc0aa..a75a27ed63ce 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9153,6 +9153,9 @@ enum {
>  #define   PUSH_CONSTANT_DEREF_DISABLE	(1 << 8)
>  #define   GEN11_TDL_CLOCK_GATING_FIX_DISABLE	(1 << 1)
>  
> +#define GEN9_ROW_CHICKEN4		_MMIO(0x48c)

s/0x48c/0xe48c/ ?

> +#define  GEN12_DISABLE_TDL_PUSH		(1 << 9)
> +
>  #define HSW_ROW_CHICKEN3		_MMIO(0xe49c)
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
>  
> -- 
> 2.21.1
>