Re: [PATCH] mailbox: pcc: Notify clients on polled completion

[lihuisong (C)]

On 6/18/2026 8:06 PM, Sudeep Holla wrote:
> On Thu, Jun 18, 2026 at 10:04:12AM +0800, lihuisong (C) wrote:
> > Hi Sudeep,
> >
> > On 6/13/2026 1:02 AM, Sudeep Holla wrote:
> > > PCC channels without a platform interrupt rely on the mailbox
> > > polling path to detect command completion.
> > >
> > > That path currently only reports transmit completion to the mailbox
> > > core, so clients that wait for their receive callback do not get
> > > notified when the command completes.
> > >
> > > Call mbox_chan_received_data() when polling observes completion on a
> > > channel without a platform IRQ, matching the interrupt-driven
> > > completion path.
> > >
> > > Reported-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> > > Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxxxxx>
> > > ---
> > >    drivers/mailbox/pcc.c | 7 ++++++-
> > >    1 file changed, 6 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> > > index 636879ae1db7..7c9451ab4527 100644
> > > --- a/drivers/mailbox/pcc.c
> > > +++ b/drivers/mailbox/pcc.c
> > > @@ -447,9 +447,14 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
> > >    static bool pcc_last_tx_done(struct mbox_chan *chan)
> > >    {
> > > +	bool ret;
> > >    	struct pcc_chan_info *pchan = chan->con_priv;
> > > -	return pcc_mbox_cmd_complete_check(pchan);
> > > +	ret = pcc_mbox_cmd_complete_check(pchan);
> > > +	if (ret && !pchan->plat_irq)
> > > +		mbox_chan_received_data(chan, NULL);
> > > +
> > > +	return ret;
> > >    }
> > The mailbox_controller.h said that .last_tx_done() is used only if
> > txdone_poll:=true && txdone_irq:=false.
> > How about add a verification at the begining of this function? like "if
> > (chan->txdone_method != MBOX_TXDONE_BY_POLL) return false;"
> > And then call mbox_chan_received_data() directly if command completed.
> Thanks, it does makes sense to me. I will have look.
>
> > This patch is ok to me if has above changes.
> > Acked-by: lihuisong@xxxxxxxxxx
> >
> >
> > But pcc mbox controller can no longer work in MBOX_TXDONE_BY_ACK after your
> > commit:
> > 3349f800609e (mailbox: pcc: Set txdone_irq/txdone_poll based on PCCT flags).
> > This may lead to above client drivers fail to send mailbox command, like
> > cppc_acpi,hisi_uncore_freq and kunpeng_hccs.
> > Because these client driver knows tx_done(knows_txdone: true), work on this
> > mode and need to call mbox_client_txdone.
> > Do you have some idea for this?
> I wonder if we can ask the platform to avoid generating interrupts in those
> case by setting/clearing "Notify on completion" in shmem. Do you think that
> would work ?
These drivers didn't work on interrupt mode.
They poll the complete status of command.
>