media: amphion: remove mutext lock in condition of wait_event

mutext_lock should not be called in condition of wait_event, otherwise,
when CONFIG_DEBUG_ATOMIC_SLEEP is enabled, we may meet the following
warning:
do not call blocking ops when !TASK_RUNNING; state=2
WARNING: CPU: 5 PID: 741 at kernel/sched/core.c:9859
__might_sleep+0x80/0xa4
Hardware name: Freescale i.MX8QM MEK (DT)
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc :
__might_sleep+0x80/0xa4 lr : __might_sleep+0x80/0xa4 sp : ffffffc0123738a0
x29: ffffffc0123738a0 x28: ffffffc009194c48 x27: ffffffc00bbc1050
x26: ffffff8814b282f0 x25: ffffff8814b280d0 x24: ffffff8814b28080
x23: 0000000000000001 x22: 0000000000000032 x21: ffffffc00bbc1000
x20: 000000000000011b x19: ffffffc009324670 x18: 00000000fffffffd
x17: 30303c5b20746120 x16: 74657320323d6574 x15: 617473203b474e49
x14: 00058b5b8b9aa1f1 x13: ffffffc00903cda0 x12: 00000000d744fcc9
x11: 000000000000001c x10: 00000000000009a0 x9 : ffffffc0090201f4
x8 : ffffff8828245000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : 00000000410fd080 x4 : 0000000000000002 x3 : ffffff8815aab4c8
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffff8828244600
Call trace:
__might_sleep+0x80/0xa4
mutex_lock+0x2c/0x80
sync_session_response+0x110/0x310
vpu_session_send_cmd+0x18c/0x244
vpu_session_start+0x38/0x70
vdec_start_session+0x1b4/0x3e0
vpu_vb2_start_streaming+0xa0/0x1c4
vb2_start_streaming+0x74/0x160
vb2_core_qbuf+0x488/0x650
vb2_qbuf+0x9c/0x100
v4l2_m2m_qbuf+0x7c/0x224
v4l2_m2m_ioctl_qbuf+0x20/0x2c
v4l_qbuf+0x50/0x6c
__video_do_ioctl+0x174/0x3f0
video_usercopy+0x210/0x7cc
video_ioctl2+0x20/0x30
v4l2_ioctl+0x48/0x6c

we need to refine check_is_responsed() to remove the mutext_lock, each
cmd has a monotonically increasing id, and cmds are executed
sequentially, so we can check the id of the last reponsed cmd, then
determine whether a command has been responded or not.

Signed-off-by: Ming Qian <[e-mail]>
CC: Xiaolei Wang <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/platform/amphion/vpu.h

···
 	struct vpu_mbox tx_type;
 	struct vpu_mbox tx_data;
 	struct vpu_mbox rx;
-	unsigned long cmd_seq;
 
 	wait_queue_head_t ack_wq;
 	struct completion cmp;
···
 
 	struct list_head cmd_q;
 	void *pending;
+	unsigned long cmd_seq;
+	atomic_long_t last_response_cmd;
 
 	struct vpu_inst_ops *ops;
 	const struct vpu_format *formats;

drivers/media/platform/amphion/vpu_cmds.c

···
 	struct vpu_cmd_request *request;
 	struct vpu_rpc_event *pkt;
 	unsigned long key;
+	atomic_long_t *last_response_cmd;
 };
 
 static struct vpu_cmd_request vpu_cmd_requests[] = {
···
 {
 	if (!cmd)
 		return;
+	if (cmd->last_response_cmd)
+		atomic_long_set(cmd->last_response_cmd, cmd->key);
 	vfree(cmd->pkt);
 	vfree(cmd);
 }
···
 		return -ENOMEM;
 
 	mutex_lock(&core->cmd_lock);
-	cmd->key = core->cmd_seq++;
+	cmd->key = ++inst->cmd_seq;
+	cmd->last_response_cmd = &inst->last_response_cmd;
 	if (key)
 		*key = cmd->key;
 	if (sync)
···
 
 static bool check_is_responsed(struct vpu_inst *inst, unsigned long key)
 {
-	struct vpu_core *core = inst->core;
-	struct vpu_cmd_t *cmd;
-	bool flag = true;
+	unsigned long last_response = atomic_long_read(&inst->last_response_cmd);
 
-	mutex_lock(&core->cmd_lock);
-	cmd = inst->pending;
-	if (cmd && key == cmd->key) {
-		flag = false;
-		goto exit;
-	}
-	list_for_each_entry(cmd, &inst->cmd_q, list) {
-		if (key == cmd->key) {
-			flag = false;
-			break;
-		}
-	}
-exit:
-	mutex_unlock(&core->cmd_lock);
+	if (key <= last_response && (last_response - key) < (ULONG_MAX >> 1))
+		return true;
 
-	return flag;
+	return false;
 }
 
 static int sync_session_response(struct vpu_inst *inst, unsigned long key, long timeout, int try)

drivers/media/platform/amphion/vpu_v4l2.c

···
 		func = &vpu->decoder;
 
 	atomic_set(&inst->ref_count, 0);
+	atomic_long_set(&inst->last_response_cmd, 0);
 	vpu_inst_get(inst);
 	inst->vpu = vpu;
 	inst->core = vpu_request_core(vpu, inst->type);