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

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Date:   Thu, 12 Dec 2019 10:20:25 +0800
From:   Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>
To:     CK Hu <ck.hu@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <wsd_upstream@...iatek.com>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 04/14] mailbox: mediatek: cmdq: clear task in channel
 before shutdown

Hi CK,

On Thu, 2019-12-12 at 10:03 +0800, CK Hu wrote:
> 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 <dennis-yc.hsieh@...iatek.com>
> > > > > > ---
> > > > > >  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
> 

sorry for not clearly explain before

call to cmdq_thread_reset() will reset thread status, which include
suspend state. the CMDQ_THR_SUSPEND_TASK will be clear after reset, thus
we can simply set CMDQ_THR_ENABLE_TASK to CMDQ_THR_ENABLED and then
thread running again.

I will add comment in both cmdq_mbox_send_data() and
cmdq_mbox_shutdown() to clarify this hardware behavior.


Regards,
Dennis

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