[PATCH v1 5/7] media: chips-media: wave5: Defer job_finish() only when a DEC_PIC was queued

[Jackson.lee]

From: Jackson Lee <jackson.lee@xxxxxxxxxxxxxxx>

Decoder instances sharing a VPU also share one v4l2_m2m job slot, released
when the running context calls v4l2_m2m_job_finish(). While draining,
device_run() defers job_finish() once EOS is sent (sent_eos), expecting a
later finish_decode() (from a DEC_PIC completion IRQ) to release the slot.

But the m2m core checks job_ready() only when a job is queued, not when it
is dispatched. A job queued while draining can run after finish_decode()
has already moved the instance to STOP and sent EOS. device_run() then runs
in STOP, issues no DEC_PIC, yet still skips job_finish() - so no IRQ, no
finish_decode(), and the shared slot is leaked, stalling every instance.
With several v4l2h264dec instances in parallel, GStreamer hangs at EOS.

Track whether the run actually queued a DEC_PIC (cmd_issued) and defer
job_finish() only then. Otherwise finish the job immediately

Fixes: a176ac5e701f ("media: chips-media: wave5: Improve performance of decoder")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jackson Lee <jackson.lee@xxxxxxxxxxxxxxx>
Signed-off-by: Nas Chung <nas.chung@xxxxxxxxxxxxxxx>
---
 .../media/platform/chips-media/wave5/wave5-vpu-dec.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c b/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
index 93f7b724d86c..f33c00cb801b 100644
--- a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
+++ b/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
@@ -1655,6 +1655,7 @@ static void wave5_vpu_dec_device_run(void *priv)
 	struct queue_status_info q_status;
 	u32 fail_res = 0;
 	int ret = 0;
+	bool cmd_issued = false;
 
 	dev_dbg(inst->dev->dev, "%s: Fill the ring buffer with new bitstream data", __func__);
 	pm_runtime_resume_and_get(inst->dev->dev);
@@ -1752,6 +1753,7 @@ static void wave5_vpu_dec_device_run(void *priv)
 			inst->retry = false;
 			if (!inst->eos)
 				inst->queuing_num--;
+			cmd_issued = true;
 		}
 		break;
 	default:
@@ -1769,8 +1771,16 @@ static void wave5_vpu_dec_device_run(void *priv)
 	 * in power and CPU time.
 	 * If EOS is passed, device_run will not call job_finish no more, it is called
 	 * only if HW is idle status in order to reduce overhead.
+	 *
+	 * Deferring job_finish() is only safe when this run actually queued a
+	 * DEC_PIC command (cmd_issued): that guarantees a completion IRQ, and
+	 * thus a later finish_decode(), will release the shared job slot. When
+	 * device_run() is entered with no command to issue (e.g. a job that was
+	 * queued while draining but reached the STOP state by the time it ran),
+	 * no IRQ follows, so finish the job here to avoid leaking the slot and
+	 * stalling every instance sharing the VPU.
 	 */
-	if (!inst->sent_eos)
+	if (!inst->sent_eos || !cmd_issued)
 		v4l2_m2m_job_finish(inst->v4l2_m2m_dev, m2m_ctx);
 }
 
-- 
2.43.0