[Intel-gfx] [PATCH v3 1/5] drm/i915/mtl: Fix Wa_16015201720 implementation

[Matt Roper]

On Wed, Mar 01, 2023 at 12:10:49PM -0800, Radhakrishna Sripada wrote:
> The commit 2357f2b271ad ("drm/i915/mtl: Initial display workarounds")
> extended the workaround Wa_16015201720 to MTL. However the registers
> that the original WA implemented moved for MTL.
> 
> Implement the workaround with the correct register.
> 
> v3: Skip clock gating for pipe C, D DMC's and fix the title
> 
> Fixes: 2357f2b271ad ("drm/i915/mtl: Initial display workarounds")
> Cc: Matt Atwood <matthew.s.atwood at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dmc.c | 26 +++++++++++++++++++-----
>  drivers/gpu/drm/i915/i915_reg.h          | 10 ++++++---
>  2 files changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
> index f70ada2357dc..b4283cf319f2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dmc.c
> +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
> @@ -389,15 +389,12 @@ static void disable_all_event_handlers(struct drm_i915_private *i915)
>  	}
>  }
>  
> -static void pipedmc_clock_gating_wa(struct drm_i915_private *i915, bool enable)
> +static void adlp_pipedmc_clock_gating_wa(struct drm_i915_private *i915, bool enable)
>  {
>  	enum pipe pipe;
>  
> -	if (DISPLAY_VER(i915) < 13)
> -		return;
> -
>  	/*
> -	 * Wa_16015201720:adl-p,dg2, mtl
> +	 * Wa_16015201720:adl-p,dg2
>  	 * The WA requires clock gating to be disabled all the time
>  	 * for pipe A and B.
>  	 * For pipe C and D clock gating needs to be disabled only
> @@ -413,6 +410,25 @@ static void pipedmc_clock_gating_wa(struct drm_i915_private *i915, bool enable)
>  				     PIPEDMC_GATING_DIS, 0);
>  }
>  
> +static void mtl_pipedmc_clock_gating_wa(struct drm_i915_private *i915)
> +{
> +	/*
> +	 * Wa_16015201720
> +	 * The WA requires clock gating to be disabled all the time
> +	 * for pipe A and B.
> +	 */
> +	intel_de_rmw(i915, GEN9_CLKGATE_DIS_0, 0,
> +		     MTL_PIPEDMC_GATING_DIS_A | MTL_PIPEDMC_GATING_DIS_B);
> +}
> +
> +static void pipedmc_clock_gating_wa(struct drm_i915_private *i915, bool enable)
> +{
> +	if (DISPLAY_VER(i915) >= 14 && enable)
> +		return mtl_pipedmc_clock_gating_wa(i915);
> +	else if (DISPLAY_VER(i915) == 13)
> +		return adlp_pipedmc_clock_gating_wa(i915, enable);

Both of these functions return 'void' so the 'return' on each of these
lines is a bit strange.  I'd remove the 'return' at the beginning of
these lines.

> +}
> +
>  void intel_dmc_enable_pipe(struct drm_i915_private *i915, enum pipe pipe)
>  {
>  	enum intel_dmc_id dmc_id = PIPE_TO_DMC_ID(pipe);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index c1efa655fb68..7c9ac5b43831 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1794,9 +1794,13 @@
>   * GEN9 clock gating regs
>   */
>  #define GEN9_CLKGATE_DIS_0		_MMIO(0x46530)
> -#define   DARBF_GATING_DIS		(1 << 27)
> -#define   PWM2_GATING_DIS		(1 << 14)
> -#define   PWM1_GATING_DIS		(1 << 13)
> +#define   DARBF_GATING_DIS		REG_BIT(27)
> +#define   MTL_PIPEDMC_GATING_DIS_A	REG_BIT(15)
> +#define   MTL_PIPEDMC_GATING_DIS_B	REG_BIT(14)
> +#define   PWM2_GATING_DIS		REG_BIT(14)
> +#define   MTL_PIPEDMC_GATING_DIS_C	REG_BIT(13)
> +#define   PWM1_GATING_DIS		REG_BIT(13)
> +#define   MTL_PIPEDMC_GATING_DIS_D	REG_BIT(12)

It's not really worth adding bits that we don't use anywhere.  I'd drop
the DIS_C and DIS_D defines here, otherwise people will wonder whether
it's a mistake that they're added but not used.

Aside from the unnecessary bits here and the returns above, the rest
looks okay, so

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

with those changes.


Matt

>  
>  #define GEN9_CLKGATE_DIS_3		_MMIO(0x46538)
>  #define   TGL_VRH_GATING_DIS		REG_BIT(31)
> -- 
> 2.34.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation