Re: [PATCH 6.18.y] mailbox: Fix NULL message support in mbox_send_message()

[Joonwon Kang <joonwonkang@google.com>]

> On Thu, May 07, 2026 at 06:21:07AM +0000, Joonwon Kang wrote:
> > diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> > index ff292b9e0be9..7a2baeca2ba4 100644
> > --- a/drivers/mailbox/pcc.c
> > +++ b/drivers/mailbox/pcc.c
> > @@ -361,7 +361,7 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
> >  	if (pchan->chan.rx_alloc)
> >  		handle = write_response(pchan);
> >
> > -	if (chan->active_req) {
> > +	if (chan->active_req != MBOX_NO_MSG) {
> >  		pcc_header = chan->active_req;
> >  		if (pcc_header->flags & PCC_CMD_COMPLETION_NOTIFY)
> >  			mbox_chan_txdone(chan, 0);
> 
> This pcc.c hunk does not apply on 6.18.y: commit 5378bdf6a611 ("mailbox/pcc:
> support mailbox management of the shared buffer") was reverted upstream by
> f82c3e62b6b8, and that revert is already queued in 6.18 as 2cafad617431.
> write_response() and the active_req-driven txdone path no longer exist in
> pcc_mbox_irq() on 6.18, so this hunk is both syntactically inapplicable and
> semantically unnecessary.
> 

Indeed. Thanks for letting me know of this. My local environment was quite
a bit behind the latest.

> Could you send a v2 omitting the pcc.c hunk? The other three hunks
> (mailbox.c, tegra-hsp.c, mailbox_controller.h) apply cleanly and I'm
> happy to queue those for 6.18.y.

Sure, I will send a new version.

Thanks,
Joonwon Kang