Re: [Intel-gfx] [PATCH] drm/i915/gt: Mask media GuC interrupts

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 4/14/2023 9:25 AM, Andi Shyti wrote:
> MTL features a dedicated media engine that operates on its
> independent GT, requiring activation of its specific interrupt
> set.
>
> Enable the necessary interrupts in a single action when the media
> engine is present, bypassing the need to iterate through all the
> GTs.
>
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> ---
> Hi,
>
> I'm starting with v0 as this patch is very different from the
> ones proposed recently.
>
> After all the discussions on this patch, I took Matt's suggestion
> since it seemed the most immediate.
>
> However, in the long run, I agree that we should have a
> specific mtl_ function for enabling interrupts.
>
> Thank you Matt and Daniele for your input.
>
> If this patch hasn't missed anything, is it too optimistic to
> expect MTL to boot? :-)

The GSC engine also has interrupts tied to the media GT and those are 
conditional, so that engine won't work with just this patch. The system 
might boot because the GSC engine gets disabled if the FW is not there, 
but IMO if we want a single function to handle both GTs we need to do it 
proper support for the engines and not hack around just the GuC.

Daniele

>
> Andi
>
>   drivers/gpu/drm/i915/gt/intel_gt_irq.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_irq.c b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> index 1b25a60391522..162a27b4c4095 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> @@ -254,7 +254,6 @@ void gen11_gt_irq_postinstall(struct intel_gt *gt)
>   {
>   	struct intel_uncore *uncore = gt->uncore;
>   	u32 irqs = GT_RENDER_USER_INTERRUPT;
> -	u32 guc_mask = intel_uc_wants_guc(&gt->uc) ? GUC_INTR_GUC2HOST : 0;
>   	u32 gsc_mask = 0;
>   	u32 dmask;
>   	u32 smask;
> @@ -309,17 +308,20 @@ void gen11_gt_irq_postinstall(struct intel_gt *gt)
>   	if (gsc_mask)
>   		intel_uncore_write(uncore, GEN11_GUNIT_CSME_INTR_MASK, ~gsc_mask);
>   
> -	if (guc_mask) {
> +	if (intel_uc_wants_guc(&gt->uc)) {
> +		u32 guc_mask = GUC_INTR_GUC2HOST;
>   		/* the enable bit is common for both GTs but the masks are separate */
> -		u32 mask = gt->type == GT_MEDIA ?
> -			REG_FIELD_PREP(ENGINE0_MASK, guc_mask) :
> -			REG_FIELD_PREP(ENGINE1_MASK, guc_mask);
> +		u32 mask = REG_FIELD_PREP(ENGINE1_MASK, guc_mask);
> +
> +		/* Mask the GuC interrupts of media engine if present */
> +		if (MEDIA_VER(gt->i915) >= 13)
> +			mask |= REG_FIELD_PREP(ENGINE0_MASK, guc_mask);
>   
>   		intel_uncore_write(uncore, GEN11_GUC_SG_INTR_ENABLE,
>   				   REG_FIELD_PREP(ENGINE1_MASK, guc_mask));
>   
>   		/* we might not be the first GT to write this reg */
> -		intel_uncore_rmw(uncore, MTL_GUC_MGUC_INTR_MASK, mask, 0);
> +		intel_uncore_write(uncore, MTL_GUC_MGUC_INTR_MASK, mask);
>   	}
>   
>   	/*