[PATCH] [RFC]drm/xe: Introduce active ccs tracking

[Tejas Upadhyay <tejas.upadhyay@intel.com>]

Current ccs_mode setting is allowed when no client has
actively opened device. Instead it should be restricted
 if there is any active ccs engine in use.

Closing device fd is always a async and may lead to show
client present even after fd is closed from user perspective.

Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
---
 drivers/gpu/drm/xe/xe_force_wake.c  | 3 +++
 drivers/gpu/drm/xe/xe_gt_ccs_mode.c | 8 ++++----
 drivers/gpu/drm/xe/xe_gt_types.h    | 6 ++++++
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_force_wake.c b/drivers/gpu/drm/xe/xe_force_wake.c
index a64c14757c84..51ab8e5dd583 100644
--- a/drivers/gpu/drm/xe/xe_force_wake.c
+++ b/drivers/gpu/drm/xe/xe_force_wake.c
@@ -195,6 +195,9 @@ int xe_force_wake_put(struct xe_force_wake *fw,
 		ret |= domain_sleep_wait(gt, domain);
 	}
 	fw->awake_domains &= ~sleep;
+	if (!(fw->awake_domains & XE_FW_GT))
+		if (gt->ccs_mode && !IS_SRIOV_VF(gt_to_xe(gt)))
+			gt->ccs_active = 0;
 	spin_unlock_irqrestore(&fw->lock, flags);
 
 	return ret;
diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
index 9360ac4de489..dbc49d595a6c 100644
--- a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
+++ b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
@@ -69,6 +69,7 @@ static void __xe_gt_apply_ccs_mode(struct xe_gt *gt, u32 num_engines)
 	}
 
 	xe_mmio_write32(&gt->mmio, CCS_MODE, mode);
+	gt->ccs_active = mode;
 
 	xe_gt_dbg(gt, "CCS_MODE=%x config:%08x, num_engines:%d, num_slices:%d\n",
 		  mode, config, num_engines, num_slices);
@@ -132,10 +133,9 @@ ccs_mode_store(struct device *kdev, struct device_attribute *attr,
 		return -EINVAL;
 	}
 
-	/* CCS mode can only be updated when there are no drm clients */
-	spin_lock(&xe->clients.lock);
-	if (xe->clients.count) {
-		spin_unlock(&xe->clients.lock);
+	/* CCS mode can only be updated when there is no active ccs_mode */
+	if (gt->ccs_active) {
+		xe_gt_info(gt, "Setting compute mode not allowed ccs_active:%d\n", gt->ccs_active);
 		return -EBUSY;
 	}
 
diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
index a287b98ee70b..791f9aef8174 100644
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -219,6 +219,12 @@ struct xe_gt {
 	 * available compute slices are allocated to it.
 	 */
 	u32 ccs_mode;
+	/**
+	 * @ccs_active: Number of compute engines active currently.
+	 * Keep track of active ccs engines to allow/deny config by next user with
+	 * new ccs_mode.
+	 */
+	u32 ccs_active;
 
 	/** @usm: unified shared memory state */
 	struct {
-- 
2.34.1