[Intel-gfx] [PATCH 1/1] drm/i915/tgl: Implement Wa_1604555607

[Tvrtko Ursulin]

On 22/11/2019 04:02, Ramalingam C wrote:
> From: Michel Thierry <michel.thierry at intel.com>
> 
> Implement Wa_1604555607 (set the DS pairing timer to 128 cycles).
> FF_MODE2 is part of the register state context, that's why it is
> implemented here.
> 
> At TGL A0 stepping, FF_MODE2 register read back is broken, hence
> disabling the WA verification.
> 
> v2: Rebased on top of the WA refactoring (Oscar)
> v3: Correctly add to ctx_workarounds_init (Michel)
> v4:
>    uncore read is used [Tvrtko]
>    Macros as used for MASK definition [Chris]
> v5:
>    Skip the Wa_1604555607 verification [Ram]
>    i915 ptr retrieved from engine. [Tvrtko]
> v6:
>    __wa_write_masked_or used with varying parameter [Tvrtko]
>    Added wa_add as a wrapper for __wa_add [Chris]
> v7:
>    WA verification is skipped on all stepping as of now [Lucas]
> 
> BSpec: 19363
> HSDES: 1604555607
> Signed-off-by: Michel Thierry <michel.thierry at intel.com>
> Signed-off-by: Ramalingam C <ramlingam.c at intel.com>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com> [v5]
> ---
>   drivers/gpu/drm/i915/gt/intel_workarounds.c | 34 ++++++++++++++++++---
>   drivers/gpu/drm/i915/i915_reg.h             |  4 +++
>   2 files changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 399acae2f33f..b11540caa92d 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -146,20 +146,33 @@ static void _wa_add(struct i915_wa_list *wal, const struct i915_wa *wa)
>   	}
>   }
>   
> -static void
> -wa_write_masked_or(struct i915_wa_list *wal, i915_reg_t reg, u32 mask,
> -		   u32 val)
> +static void wa_add(struct i915_wa_list *wal, i915_reg_t reg, u32 mask,
> +		   u32 val, u32 read_mask)
>   {
>   	struct i915_wa wa = {
>   		.reg  = reg,
>   		.mask = mask,
>   		.val  = val,
> -		.read = mask,
> +		.read = read_mask,
>   	};
>   
>   	_wa_add(wal, &wa);
>   }
>   
> +static void
> +__wa_write_masked_or(struct i915_wa_list *wal, i915_reg_t reg, u32 mask,
> +		     u32 val, u32 read_mask)
> +{
> +	wa_add(wal, reg, mask, val, read_mask);
> +}
> +
> +static void
> +wa_write_masked_or(struct i915_wa_list *wal, i915_reg_t reg, u32 mask,
> +		   u32 val)
> +{
> +	__wa_write_masked_or(wal, reg, mask, val, mask);

Minor point - not sure about the need for this helper now, you could 
just call wa_add from here.

> +}
> +
>   static void
>   wa_masked_en(struct i915_wa_list *wal, i915_reg_t reg, u32 val)
>   {
> @@ -568,9 +581,22 @@ 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)
>   {
> +	u32 val;
> +
>   	/* Wa_1409142259:tgl */
>   	WA_SET_BIT_MASKED(GEN11_COMMON_SLICE_CHICKEN3,
>   			  GEN12_DISABLE_CPS_AWARE_COLOR_PIPE);
> +
> +	/* Wa_1604555607:tgl */
> +	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
> +	 * the read of FF_MODE2.
> +	 */
> +	__wa_write_masked_or(wal, FF_MODE2, FF_MODE2_TDS_TIMER_MASK, val, 0);

If I was a betting man I'd bet no one will ever remember to add the 
verification back. So I have to say I disagree with Lucas on this point. 
Someone do a casting vote please. :)

We know it will remain broken until at least after B0?

>   }
>   
>   static void
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 94d0f593eeb7..a99fdf8ea53b 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7922,6 +7922,10 @@ enum {
>   #define   PIXEL_ROUNDING_TRUNC_FB_PASSTHRU 	(1 << 15)
>   #define   PER_PIXEL_ALPHA_BYPASS_EN		(1 << 7)
>   
> +#define FF_MODE2			_MMIO(0x6604)
> +#define   FF_MODE2_TDS_TIMER_MASK	REG_GENMASK(23, 16)
> +#define   FF_MODE2_TDS_TIMER_128	REG_FIELD_PREP(FF_MODE2_TDS_TIMER_MASK, 4)
> +
>   /* PCH */
>   
>   #define PCH_DISPLAY_BASE	0xc0000u
> 

Regards,

Tvrtko