Re: [Intel-gfx] [PATCH 5/5] drm/i915/guc: enable only the user interrupt when using GuC submission

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

On 1/5/2021 3:38 PM, Chris Wilson wrote:
> Quoting Daniele Ceraolo Spurio (2021-01-05 23:19:47)
>> In GuC submission mode the CS is owned by the GuC FW, so all CS status
>> interrupts are handled by it. We only need the user interrupt as that
>> signals request completion.
>>
>> Since we're now starting the engines directly in GuC submission mode
>> when selected, we can stop switching back and forth between the
>> execlists and the GuC programming and select directly the correct
>> interrupt mask.
>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Cc: Matthew Brost <matthew.brost@intel.com>
>> Cc: John Harrison <john.c.harrison@intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_gt_irq.c        | 18 ++++++-----
>>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 31 -------------------
>>   2 files changed, 11 insertions(+), 38 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_irq.c b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
>> index 9830342aa6f4..7b2b8cb2d2be 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt_irq.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
>> @@ -237,14 +237,18 @@ void gen11_gt_irq_reset(struct intel_gt *gt)
>>   
>>   void gen11_gt_irq_postinstall(struct intel_gt *gt)
>>   {
>> -       const u32 irqs =
>> -               GT_CS_MASTER_ERROR_INTERRUPT |
>> -               GT_RENDER_USER_INTERRUPT |
>> -               GT_CONTEXT_SWITCH_INTERRUPT |
>> -               GT_WAIT_SEMAPHORE_INTERRUPT;
>>          struct intel_uncore *uncore = gt->uncore;
>> -       const u32 dmask = irqs << 16 | irqs;
>> -       const u32 smask = irqs << 16;
>> +       u32 irqs = GT_RENDER_USER_INTERRUPT;
>> +       u32 dmask;
>> +       u32 smask;
>> +
>> +       if (!intel_uc_wants_guc_submission(&gt->uc))
>> +               irqs |= GT_CS_MASTER_ERROR_INTERRUPT |
>> +                       GT_CONTEXT_SWITCH_INTERRUPT |
>> +                       GT_WAIT_SEMAPHORE_INTERRUPT;
> Hmm, we should stop performing this by default then, and make the
> execlists setup request the interrupt vector it desires.
>
> That's certainly a bit more fiddly to untangle the packed iir across
> multiple gen. :|

I had considered that, but this is a gt-level setup while the execlists 
submission code is currently all engine-based, so I couldn't find a good 
place to move this to and I didn't want to add a new function just for 
it. Any preference?

Daniele

> -Chris

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