Re: [RFC PATCH 1/6] drm/i915: Remove Gen9 WAs with no effect

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Oscar Mateo <oscar.mateo@intel.com> writes:

> GEN8_CONFIG0 (0xD00) is a protected by a lock (bit 31) which is set by
> the BIOS, so there is no way we can enable the three chicken bits
> mandated by the WA (the BIOS should be doing it instead).
>
> v2: Rebased
> v3: Standalone patch
>
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h | 3 ---
>  drivers/gpu/drm/i915/intel_pm.c | 3 ---
>  2 files changed, 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index f0f8f60..7991d90 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -355,9 +355,6 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
>  #define   ECOCHK_PPGTT_WT_HSW		(0x2<<3)
>  #define   ECOCHK_PPGTT_WB_HSW		(0x3<<3)
>  
> -#define GEN8_CONFIG0			_MMIO(0xD00)
> -#define  GEN9_DEFAULT_FIXES		(1 << 3 | 1 << 2 | 1 << 1)
> -
>  #define GAC_ECO_BITS			_MMIO(0x14090)
>  #define   ECOBITS_SNB_BIT		(1<<13)
>  #define   ECOBITS_PPGTT_CACHE64B	(3<<8)
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index e09377d..5bd49a7 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -75,9 +75,6 @@ static void gen9_init_clock_gating(struct drm_i915_private *dev_priv)
>  	I915_WRITE(CHICKEN_PAR1_1,
>  		   I915_READ(CHICKEN_PAR1_1) | SKL_EDP_PSR_FIX_RDWRAP);
>  
> -	I915_WRITE(GEN8_CONFIG0,
> -		   I915_READ(GEN8_CONFIG0) | GEN9_DEFAULT_FIXES);
> -

I am pondering if we should do a verifying read for workarounds
and chickens in general.

Also my kbl bios seem to omit all of these with lock being on :P

Patch is,
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

-Mika

>  	/* WaEnableChickenDCPR:skl,bxt,kbl,glk,cfl */
>  	I915_WRITE(GEN8_CHICKEN_DCPR_1,
>  		   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
> -- 
> 1.9.1
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