drm/msm: Add SYSPROF param (v2)

Add a SYSPROF param for system profiling tools like Mesa's pps-producer
(perfetto) to control behavior related to system-wide performance
counter collection.  In particular, for profiling, one wants to ensure
that GPU context switches do not effect perfcounter state, and might
want to suppress suspend (which would cause counters to lose state).

v2: Swap the order in msm_file_private_set_sysprof() [sboyd] and
    initialize the sysprof_active refcount to one (because the under/
    overflow checking in refcount_t doesn't expect a 0->1 transition)
    meaning that values greater than 1 means sysprof is active.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220304005317.776110-4-robdclark@gmail.com

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
index 7cb158bcbcf6..79b6ccd6ce64 100644
--- a/drivers/gpu/drm/msm/msm_submitqueue.c
+++ b/drivers/gpu/drm/msm/msm_submitqueue.c
@@ -7,6 +7,45 @@
 
 #include "msm_gpu.h"
 
+int msm_file_private_set_sysprof(struct msm_file_private *ctx,
+				 struct msm_gpu *gpu, int sysprof)
+{
+	/*
+	 * Since pm_runtime and sysprof_active are both refcounts, we
+	 * call apply the new value first, and then unwind the previous
+	 * value
+	 */
+
+	switch (sysprof) {
+	default:
+		return -EINVAL;
+	case 2:
+		pm_runtime_get_sync(&gpu->pdev->dev);
+		fallthrough;
+	case 1:
+		refcount_inc(&gpu->sysprof_active);
+		fallthrough;
+	case 0:
+		break;
+	}
+
+	/* unwind old value: */
+	switch (ctx->sysprof) {
+	case 2:
+		pm_runtime_put_autosuspend(&gpu->pdev->dev);
+		fallthrough;
+	case 1:
+		refcount_dec(&gpu->sysprof_active);
+		fallthrough;
+	case 0:
+		break;
+	}
+
+	ctx->sysprof = sysprof;
+
+	return 0;
+}
+
 void __msm_file_private_destroy(struct kref *kref)
 {
 	struct msm_file_private *ctx = container_of(kref,