[PATCH v2] drm/i915/guc: Enable DUAL_QUEUE_WA for newer platforms

[Daniele Ceraolo Spurio]

On 4/28/2025 6:02 PM, Julia Filipchuk wrote:
> For newer platforms (post DG2) hardware intentionally stalls on
> submisstion of concurrent RCS and CCS of different address spaces. With

typo submisstion

> this workaround GuC will never schedule such conlicting contexts;
> preventing detection of a stall as a hang.
>
> GuC specs recommend to enable this for all platforms starting from MTL
> supporting CCS.
>
> v2: Use existing macros for version check. (Jani)
>
> Signed-off-by: Julia Filipchuk <julia.filipchuk at intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 9df80c325fc1..a4019d3e71a8 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> @@ -313,8 +313,12 @@ static u32 guc_ctl_wa_flags(struct intel_guc *guc)
>   	 *
>   	 * The same WA bit is used for both and 22011391025 is applicable to
>   	 * all DG2.
> +	 *
> +	 * Platforms post DG2 prevent behavior in hardware. This is implicitly
> +	 * enabled to give guc management over CCS scheduling.

Saying "implicitly enabled" here is a bit confusing, since we're doing 
an explicit enabling of the flag. Also, GuC already has management over 
CCS scheduling, we just want to change the way it does the scheduling. 
Maybe just say something like:
"Platforms post DG2 fix this issue in hardware by stalling submissions; 
to have the GuC avoid such stalls, we enable this flag on those 
platforms as well."

>   	 */
> -	if (IS_DG2(gt->i915))
> +	if (IS_DG2(gt->i915) ||
> +	    (CCS_MASK(gt) && GRAPHICS_VER_FULL((gt)->i915) >= IP_VER(12, 70)))

Unneeded parentheses around the gt variable

>   		flags |= GUC_WA_DUAL_QUEUE;
>   
>   	/* Wa_22011802037: graphics version 11/12 */
> @@ -322,8 +326,7 @@ static u32 guc_ctl_wa_flags(struct intel_guc *guc)
>   		flags |= GUC_WA_PRE_PARSER;
>   
>   	/*
> -	 * Wa_22012727170
> -	 * Wa_22012727685
> +	 * Wa_22012727170 Wa_22012727685

unneeded change.

Daniele

>   	 */
>   	if (IS_DG2_G11(gt->i915))
>   		flags |= GUC_WA_CONTEXT_ISOLATION;