Re: [PATCH 1/3] mailbox: pcc: Notify clients on polled completion

[Adam Young <adam@younglogic.com>]

On 7/17/26 03:56, 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@arm.com>
> Acked-by: Huisong Li <lihuisong@huawei.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
> ---
>   drivers/mailbox/pcc.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 636879ae1db7..d96b8b54e77e 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -449,7 +449,15 @@ static bool pcc_last_tx_done(struct mbox_chan *chan)
>   {
>   	struct pcc_chan_info *pchan = chan->con_priv;
>   
> -	return pcc_mbox_cmd_complete_check(pchan);
> +	if (!(chan->txdone_method & MBOX_TXDONE_BY_POLL))
> +		return false;
> +
> +	if (!pcc_mbox_cmd_complete_check(pchan))
> +		return false;
> +
> +	mbox_chan_received_data(chan, NULL);
> +
> +	return true;
>   }
>   
>   /**

My code doesn't poll, so I cannot really claim to have tested it, but it 
does not break the existing IRQ based driver mechanism.

I can claim to have read through the code and confirm that it is 
comparable to what happens on the IRQ case:   It clears the cmd_complete 
field and calls mbox_chan_received_data. However, it does not clear 
pchan->chan_in_use = false; (Which should now be a WRITE_ONCE) and I 
would like to confirm that is not an oversight before providing a 
reviewed-by tag.