[Intel-gfx] [PATCH 2/2] drm/i915/mtl: Disable MC6 for MTL A step

[Rodrigo Vivi]

On Wed, Mar 08, 2023 at 03:51:09PM +0530, Badal Nilawar wrote:
> The Wa_14017073508 require to send Media Busy/Idle mailbox while
> accessing Media tile. As of now it is getting handled while __gt_unpark,
> __gt_park. But there are various corner cases where forcewakes are taken
> without __gt_unpark i.e. without sending Busy Mailbox especially during
> register reads. Forcewakes are taken without busy mailbox leads to
> GPU HANG. So bringing mailbox calls under forcewake calls are no feasible
> option as forcewake calls are atomic and mailbox calls are blocking.
> The issue already fixed in B step so disabling MC6 on A step and
> reverting previous commits which handles Wa_14017073508
> 
> Fixes: 8f70f1ec587d ("drm/i915/mtl: Add Wa_14017073508 for SAMedia")
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Signed-off-by: Badal Nilawar <badal.nilawar at intel.com>

This patch should probably come before the revert itself.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_rc6.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
> index 5c91622dfca4..f4150f61f39c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6.c
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
> @@ -486,6 +486,7 @@ static bool bxt_check_bios_rc6_setup(struct intel_rc6 *rc6)
>  static bool rc6_supported(struct intel_rc6 *rc6)
>  {
>  	struct drm_i915_private *i915 = rc6_to_i915(rc6);
> +	struct intel_gt *gt = rc6_to_gt(rc6);
>  
>  	if (!HAS_RC6(i915))
>  		return false;
> @@ -502,6 +503,13 @@ static bool rc6_supported(struct intel_rc6 *rc6)
>  		return false;
>  	}
>  
> +	if (IS_MTL_MEDIA_STEP(gt->i915, STEP_A0, STEP_B0) &&
> +	    gt->type == GT_MEDIA) {
> +		drm_notice(&i915->drm,
> +			   "Media RC6 disabled on A step\n");
> +		return false;
> +	}
> +
>  	return true;
>  }
>  
> -- 
> 2.25.1
>