[PATCH v2 1/3] mailbox: mtk-cmdq: Remove pm_runtime APIs from cmdq_mbox_send_data()

[Jason-JH Lin]

pm_runtime_get_sync() and pm_runtime_put_autosuspend() were previously
called in cmdq_mbox_send_data(), which is under a spinlock in msg_submit()
(mailbox.c). This caused lockdep warnings such as "sleeping function
called from invalid context" when running with lockdebug enabled.

The BUG report:
  BUG: sleeping function called from invalid context at 
drivers/base/power/runtime.c:1164
  in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 3616, name: 
kworker/u17:3
    preempt_count: 1, expected: 0
    RCU nest depth: 0, expected: 0
    INFO: lockdep is turned off.
    irq event stamp: 0
    CPU: 1 PID: 3616 Comm: kworker/u17:3 Not tainted 
6.1.87-lockdep-14133-g26e933aca785 #1
    Hardware name: Google Ciri sku0/unprovisioned board (DT)
    Workqueue: imgsys_runner imgsys_runner_func
    Call trace:
     dump_backtrace+0x100/0x120
     show_stack+0x20/0x2c
     dump_stack_lvl+0x84/0xb4
     dump_stack+0x18/0x48
     __might_resched+0x354/0x4c0
     __might_sleep+0x98/0xe4
     __pm_runtime_resume+0x70/0x124
     cmdq_mbox_send_data+0xe4/0xb1c
     msg_submit+0x194/0x2dc
     mbox_send_message+0x190/0x330
     imgsys_cmdq_sendtask+0x1618/0x2224
     imgsys_runner_func+0xac/0x11c
     process_one_work+0x638/0xf84
     worker_thread+0x808/0xcd0
     kthread+0x24c/0x324
     ret_from_fork+0x10/0x20

Additionally, pm_runtime_put_autosuspend() should be invoked from the
GCE IRQ handler to ensure the hardware has actually completed its work.

To resolve these issues, remove the pm_runtime calls from
cmdq_mbox_send_data() and delegate power management responsibilities
to the client driver.

Fixes: 8afe816b0c99 ("mailbox: mtk-cmdq-mailbox: Implement Runtime PM with 
autosuspend")
Signed-off-by: Jason-JH Lin <jason-jh....@mediatek.com>
---
 drivers/mailbox/mtk-cmdq-mailbox.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c 
b/drivers/mailbox/mtk-cmdq-mailbox.c
index 532929916e99..654a60f63756 100644
--- a/drivers/mailbox/mtk-cmdq-mailbox.c
+++ b/drivers/mailbox/mtk-cmdq-mailbox.c
@@ -379,20 +379,13 @@ static int cmdq_mbox_send_data(struct mbox_chan *chan, 
void *data)
        struct cmdq *cmdq = dev_get_drvdata(chan->mbox->dev);
        struct cmdq_task *task;
        unsigned long curr_pa, end_pa;
-       int ret;
 
        /* Client should not flush new tasks if suspended. */
        WARN_ON(cmdq->suspended);
 
-       ret = pm_runtime_get_sync(cmdq->mbox.dev);
-       if (ret < 0)
-               return ret;
-
        task = kzalloc(sizeof(*task), GFP_ATOMIC);
-       if (!task) {
-               pm_runtime_put_autosuspend(cmdq->mbox.dev);
+       if (!task)
                return -ENOMEM;
-       }
 
        task->cmdq = cmdq;
        INIT_LIST_HEAD(&task->list_entry);
@@ -439,9 +432,6 @@ static int cmdq_mbox_send_data(struct mbox_chan *chan, void 
*data)
        }
        list_move_tail(&task->list_entry, &thread->task_busy_list);
 
-       pm_runtime_mark_last_busy(cmdq->mbox.dev);
-       pm_runtime_put_autosuspend(cmdq->mbox.dev);
-
        return 0;
 }
 
-- 
2.43.0