Tested-by: Adam Young <admiyo@os.amperecomputing.com>
On 10/16/25 15:08, Sudeep Holla wrote:
> Some platforms may leave a responder interrupt pending from earlier
> transactions. If a PCC responder channel has a pending interrupt when
> the controller starts up, enabling the IRQ line without first clearing
> the condition can lead to a spurious interrupt which could disrupt other
> transmissions if the IRQ is shared.
>
> Explicitly clear any pending responder interrupt before enabling the IRQ
> to ensure a clean start. Acknowledge the responder channel via
> pcc_chan_acknowledge() in startup before requesting/enablement of the
> IRQ. This ensures a clean baseline for the first transfer/receiption
> of the notification/response.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
> drivers/mailbox/pcc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 2829ec51b47f..418007020439 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -468,6 +468,12 @@ static int pcc_startup(struct mbox_chan *chan)
> unsigned long irqflags;
> int rc;
>
> + /*
> + * Clear and acknowledge any pending interrupts on responder channel
> + * before enabling the interrupt
> + */
> + pcc_chan_acknowledge(pchan);
> +
> if (pchan->plat_irq > 0) {
> irqflags = pcc_chan_plat_irq_can_be_shared(pchan) ?
> IRQF_SHARED | IRQF_ONESHOT : 0;
>