Subject: Re: [PATCH v2 04/14] mailbox: mediatek: cmdq: clear task in channel before shutdown

From: CK Hu <[email-masked]>
Date: Thu, 12 Dec 2019 10:03:22 +0800

Hi, Dennis:

On Thu, 2019-12-12 at 09:51 +0800, Dennis-YC Hsieh wrote:
> Hi CK,
> 
> On Thu, 2019-12-12 at 09:31 +0800, CK Hu wrote:
> > Hi, Dennis:
> > 
> > On Thu, 2019-12-12 at 09:13 +0800, Dennis-YC Hsieh wrote:
> > > Hi CK,
> > > 
> > > On Tue, 2019-12-10 at 10:49 +0800, CK Hu wrote:
> > > > Hi, Dennis:
> > > > 
> > > > On Wed, 2019-11-27 at 09:58 +0800, Dennis YC Hsieh wrote:
> > > > > Do success callback in channel when shutdown. For those task not finish,
> > > > > callback with error code thus client has chance to cleanup or reset.
> > > > > 
> > > > > Signed-off-by: Dennis YC Hsieh <[email-masked]>
> > > > > ---
> > > > >  drivers/mailbox/mtk-cmdq-mailbox.c | 26 ++++++++++++++++++++++++++
> > > > >  1 file changed, 26 insertions(+)
> > > > > 
> > > > > diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
> > > > > index fd519b6f518b..c12a768d1175 100644
> > > > > --- a/drivers/mailbox/mtk-cmdq-mailbox.c
> > > > > +++ b/drivers/mailbox/mtk-cmdq-mailbox.c
> > > > > @@ -450,6 +450,32 @@ static int cmdq_mbox_startup(struct mbox_chan *chan)
> > > > >  
> > > > >  static void cmdq_mbox_shutdown(struct mbox_chan *chan)
> > > > >  {
> > > > > +	struct cmdq_thread *thread = (struct cmdq_thread *)chan->con_priv;
> > > > > +	struct cmdq *cmdq = dev_get_drvdata(chan->mbox->dev);
> > > > > +	struct cmdq_task *task, *tmp;
> > > > > +	unsigned long flags;
> > > > > +
> > > > > +	spin_lock_irqsave(&thread->chan->lock, flags);
> > > > > +	if (list_empty(&thread->task_busy_list))
> > > > > +		goto done;
> > > > > +
> > > > > +	WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> > > > > +
> > > > > +	/* make sure executed tasks have success callback */
> > > > > +	cmdq_thread_irq_handler(cmdq, thread);
> > > > > +	if (list_empty(&thread->task_busy_list))
> > > > > +		goto done;
> > > > > +
> > > > > +	list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
> > > > > +				 list_entry) {
> > > > > +		cmdq_task_exec_done(task, -ECONNABORTED);
> > > > > +		kfree(task);
> > > > > +	}
> > > > > +
> > > > > +	cmdq_thread_disable(cmdq, thread);
> > > > > +	clk_disable(cmdq->clock);
> > > > > +done:
> > > > 
> > > > cmdq_thread_resume(thread);
> > > > 
> > > > Regards,
> > > > CK
> > > > 
> > > 
> > > Call resume here will cause violation. The thread->task_busy_list empty
> > > means no task work in gce and thread state should already disable
> > > without clock, which is what we want since client try to shut down this
> > > mbox channel. So I think we don't need resume here.
> > > 
> > 
> > OK. When client free channel, thread is suspended. Then client request
> > channel, where do you resume thread?
> > 
> 
> when client send new pkt to new channel, cmdq_mbox_send_data() will
> enable thread.

in cmdq_mbox_send_data(), it would run below command:

WARN_ON(clk_enable(cmdq->clock) < 0);
WARN_ON(cmdq_thread_reset(cmdq, thread) < 0);

writel(task->pa_base, thread->base + CMDQ_THR_CURR_ADDR);
writel(task->pa_base + pkt->cmd_buf_size,
       thread->base + CMDQ_THR_END_ADDR);
writel(thread->priority, thread->base + CMDQ_THR_PRIORITY);
writel(CMDQ_THR_IRQ_EN, thread->base + CMDQ_THR_IRQ_ENABLE);
writel(CMDQ_THR_ENABLED, thread->base + CMDQ_THR_ENABLE_TASK);

Do you mean CMDQ_THR_ENABLE_TASK is set to CMDQ_THR_ENABLED, then
CMDQ_THR_SUSPEND_TASK would be automatically set to CMDQ_THR_RESUME? If
this hardware work in so special behavior, please add comment for this.

Regards,
CK

> 
> 
> Regards,
> Dennis
> 
> > Regards,
> > CK
> > 
> > > 
> > > Regards,
> > > Dennis
> > > 
> > > > > +	spin_unlock_irqrestore(&thread->chan->lock, flags);
> > > > >  }
> > > > >  
> > > > >  static const struct mbox_chan_ops cmdq_mbox_chan_ops = {
> > > > 
> > > > 
> > > 
> > > 
> > 
> > 
> 
> 

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