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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 18 Apr 2025, Julia Filipchuk <julia.filipchuk@intel.com> wrote:
> For newer platforms (post DG2) hardware intentionally stalls on
> submisstion of concurrent RCS and CCS of different address spaces. With
> 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.
>
> Signed-off-by: Julia Filipchuk <julia.filipchuk@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_gt.h     | 8 ++++++++
>  drivers/gpu/drm/i915/gt/uc/intel_guc.c | 9 ++++++---
>  2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h
> index 998ca029b73a..2f86b2291826 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt.h
> @@ -24,6 +24,14 @@ struct drm_printer;
>  	 GRAPHICS_VER_FULL((gt)->i915) >= (from) && \
>  	 GRAPHICS_VER_FULL((gt)->i915) <= (until)))
>  
> +/*
> + * Check that the GT is a graphics GT and has atleast minimum IP version.
> + */
> +#define IS_GFX_GT_IP_ATLEAST(gt, from) ( \
> +	BUILD_BUG_ON_ZERO((from) < IP_VER(2, 0)) + \
> +	((gt)->type != GT_MEDIA && \
> +	 GRAPHICS_VER_FULL((gt)->i915) >= (from)))
> +
>  /*
>   * Check that the GT is a media GT and has an IP version within the
>   * specified range (inclusive).
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 9df80c325fc1..70c83c1588e9 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.
>  	 */
> -	if (IS_DG2(gt->i915))
> +	if (IS_DG2(gt->i915) ||
> +	    (CCS_MASK(gt) && IS_GFX_GT_IP_ATLEAST(gt, IP_VER(12, 70))))
>  		flags |= GUC_WA_DUAL_QUEUE;

	GRAPHICS_VER_FULL((gt)->i915) >= IP_VER(12, 70)

You don't need an extra macro for a single use case that is covered by
existing macros.

BR,
Jani.


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

-- 
Jani Nikula, Intel