[PATCH 4/5] drm/xe/oa: Assign hwe for OAM_SAG

[Umesh Nerlige Ramappa]

On Tue, Jun 03, 2025 at 01:21:32PM -0700, Ashutosh Dixit wrote:
>Because OAM_SAG doesn't have an attached hwe, assign another hwe belonging
>to the same gt (and different OAM unit) to OAM_SAG. A hwe is needed for
>batch submissions to program OA HW.
>
>Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
>---
> drivers/gpu/drm/xe/xe_oa.c       | 54 +++++++++++++++++++-------------
> drivers/gpu/drm/xe/xe_oa_types.h |  3 ++
> 2 files changed, 35 insertions(+), 22 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
>index 4d6d9f0189a83..35157424010bb 100644
>--- a/drivers/gpu/drm/xe/xe_oa.c
>+++ b/drivers/gpu/drm/xe/xe_oa.c
>@@ -1923,37 +1923,45 @@ u16 xe_oa_unit_id(struct xe_hw_engine *hwe)
> 		hwe->oa_unit->oa_unit_id : U16_MAX;
> }
>
>+/* A hwe must be assigned to stream/oa_unit for batch submissions */
> static int xe_oa_assign_hwe(struct xe_oa *oa, struct xe_oa_open_param *param)
> {
>-	struct xe_gt *gt;
>-	int i, ret = 0;
>+	struct xe_hw_engine *hwe;
>+	enum xe_hw_engine_id id;
>+	int ret = 0;
>+
>+	/* If not provided, OA unit defaults to OA unit 0 as per uapi */
>+	if (!param->oa_unit)
>+		param->oa_unit = &xe_device_get_gt(oa->xe, 0)->oa.oa_unit[0];
>
>+	/* When we have an exec_q, get hwe from the exec_q */
> 	if (param->exec_q) {
>-		/* When we have an exec_q, get hwe from the exec_q */
> 		param->hwe = xe_gt_hw_engine(param->exec_q->gt, param->exec_q->class,
> 					     param->engine_instance, true);
>-	} else {
>-		struct xe_hw_engine *hwe;
>-		enum xe_hw_engine_id id;
>-
>-		/* Else just get the first hwe attached to the oa unit */
>-		for_each_gt(gt, oa->xe, i) {
>-			for_each_hw_engine(hwe, gt, id) {
>-				if (hwe->oa_unit == param->oa_unit) {
>-					param->hwe = hwe;
>-					goto out;
>-				}
>-			}
>-		}
>+		if (!param->hwe || param->hwe->oa_unit != param->oa_unit)
>+			goto err;
>+		goto out;
> 	}
>-out:
>-	if (!param->hwe || param->hwe->oa_unit != param->oa_unit) {
>-		drm_dbg(&oa->xe->drm, "Unable to find hwe (%d, %d) for OA unit ID %d\n",
>-			param->exec_q ? param->exec_q->class : -1,
>-			param->engine_instance, param->oa_unit->oa_unit_id);
>-		ret = -EINVAL;
>+
>+	/* Else just get the first hwe attached to the oa unit */
>+	for_each_hw_engine(hwe, param->oa_unit->gt, id) {
>+		if (hwe->oa_unit == param->oa_unit) {
>+			param->hwe = hwe;
>+			goto out;
>+		}
> 	}
>
>+	/* If we still didn't find a hwe, just get one from the same gt */
>+	for_each_hw_engine(hwe, param->oa_unit->gt, id) {

Not sure if for_each_hw_engine omits reserved engines. If we should not 
use reserved engines, we should check for that here using 
xe_hw_engine_is_reserved(). Also, maybe we should only try to submit the 
batch on engine classes supported by OA. Submitting the batch from other 
engines (like bcs) is not really tested.

Thanks,
Umesh

>+		param->hwe = hwe;
>+		goto out;
>+	}
>+err:
>+	drm_dbg(&oa->xe->drm, "Unable to find hwe (%d, %d) for OA unit ID %d\n",
>+		param->exec_q ? param->exec_q->class : -1,
>+		param->engine_instance, param->oa_unit->oa_unit_id);
>+	ret = -EINVAL;
>+out:
> 	return ret;
> }
>
>@@ -2578,6 +2586,8 @@ static void __xe_oa_init_oa_units(struct xe_gt *gt)
> 				DRM_XE_OA_UNIT_TYPE_OAM_SAG : DRM_XE_OA_UNIT_TYPE_OAM;
> 		}
>
>+		u->gt = gt;
>+
> 		xe_mmio_write32(&gt->mmio, u->regs.oa_ctrl, 0);
>
> 		/* Ensure MMIO trigger remains disabled till there is a stream */
>diff --git a/drivers/gpu/drm/xe/xe_oa_types.h b/drivers/gpu/drm/xe/xe_oa_types.h
>index a01c85931e2a5..2628f78c4e8dc 100644
>--- a/drivers/gpu/drm/xe/xe_oa_types.h
>+++ b/drivers/gpu/drm/xe/xe_oa_types.h
>@@ -95,6 +95,9 @@ struct xe_oa_unit {
> 	/** @oa_unit_id: identifier for the OA unit */
> 	u16 oa_unit_id;
>
>+	/** @gt: gt associated with the OA unit */
>+	struct xe_gt *gt;
>+
> 	/** @type: Type of OA unit - OAM, OAG etc. */
> 	enum drm_xe_oa_unit_type type;
>
>-- 
>2.48.1
>