[PATCH v3] drm/amd: Check that VPE has reached DPM0 in idle handler

["Mario Limonciello (AMD)" <superm1@kernel.org>]

From: Mario Limonciello <mario.limonciello@amd.com>

[Why]
Newer VPE microcode has functionality that will decrease DPM level
only when a workload has run for 2 or more seconds.  If VPE is turned
off before this DPM decrease, the SOC can get stuck with a higher
DPM level.

This can happen from amdgpu's ring buffer test because it's a short
quick workload for VPE and VPE is turned off after 1s.

[How]
In idle handler besides checking fences are drained check that VPE DPM
level is really is at DPM0. If not, schedule delayed work again until
it is.

Cc: Peyton.Lee@amd.com
Reported-by: Sultan Alsawaf <sultan@kerneltoast.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4615
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v3:
 * Use label to avoid a register read if fences active
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vpe.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vpe.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vpe.c
index 474bfe36c0c2f..e8e512de5992a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vpe.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vpe.c
@@ -326,14 +326,23 @@ static void vpe_idle_work_handler(struct work_struct *work)
 {
 	struct amdgpu_device *adev =
 		container_of(work, struct amdgpu_device, vpe.idle_work.work);
+	struct amdgpu_vpe *vpe = &adev->vpe;
 	unsigned int fences = 0;
+	uint32_t dpm_level;
 
 	fences += amdgpu_fence_count_emitted(&adev->vpe.ring);
+	if (fences)
+		goto reschedule;
 
-	if (fences == 0)
+	dpm_level = adev->pm.dpm_enabled ?
+		    RREG32(vpe_get_reg_offset(vpe, 0, vpe->regs.dpm_request_lv)) : 0;
+	if (!dpm_level) {
 		amdgpu_device_ip_set_powergating_state(adev, AMD_IP_BLOCK_TYPE_VPE, AMD_PG_STATE_GATE);
-	else
-		schedule_delayed_work(&adev->vpe.idle_work, VPE_IDLE_TIMEOUT);
+		return;
+	}
+
+reschedule:
+	schedule_delayed_work(&adev->vpe.idle_work, VPE_IDLE_TIMEOUT);
 }
 
 static int vpe_common_init(struct amdgpu_vpe *vpe)
-- 
2.43.0