[PATCH 6/7] drm/xe/gt: Drop third submission for default context

[Lucas De Marchi]

On Fri, Jul 04, 2025 at 12:21:50PM +0100, Tvrtko Ursulin wrote:
>
>On 03/07/2025 23:41, Lucas De Marchi wrote:
>>There's no need to submit the nop job again on the first queue. Any
>>state needed is already saved when the first LRC is switched out. The
>>comment is a little misleading regarding indirect W/A: first of all
>>there's still no indirect W/A enabled and secondly, even after they are,
>>there's no need to submit this job again for having their state
>>propagated: the indirect W/A will actually run on every LRC switch.
>>
>>Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
>>---
>>  drivers/gpu/drm/xe/xe_gt.c | 8 --------
>>  1 file changed, 8 deletions(-)
>>
>>diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
>>index 67425e37c2187..439e7c703ed84 100644
>>--- a/drivers/gpu/drm/xe/xe_gt.c
>>+++ b/drivers/gpu/drm/xe/xe_gt.c
>>@@ -361,14 +361,6 @@ int xe_gt_record_default_lrcs(struct xe_gt *gt)
>>  			goto put_nop_q;
>>  		}
>>-		/* Reload golden LRC to record the effect of any indirect W/A */
>>-		err = emit_nop_job(gt, q);
>>-		if (err) {
>>-			xe_gt_err(gt, "hwe %s: emit_nop_job failed (%pe) guc_id=%u\n",
>>-				  hwe->name, ERR_PTR(err), q->guc->id);
>>-			goto put_nop_q;
>>-		}
>>-
>>  		xe_map_memcpy_from(xe, default_lrc,
>>  				   &q->lrc[0]->bo->vmap,
>>  				   xe_lrc_pphwsp_offset(q->lrc[0]),
>>
>
>Wasn't it also racy to memcpy from q's LRC without guaranteeing 
>context save had completed? I don't think dma_fence_wait in 
>emit_nop_job guarantees it. If that is so this patch should actually 
>have Fixes: added and commit message adjusted accordingly.

I don't think it really fixes anything, it's just pointless to do it.
It would just save the same information from the first time it executed
even if there was a race.

Lucas De Marchi

>
>Regards,
>
>Tvrtko
>