linux-kernel - Re: [PATCH 6/6] mailbox: pcc: Clear any pending responder interrupts before enabling it

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d46a659d-6571-40e4-9c79-9a69ec919bad@amperemail.onmicrosoft.com>
Date: Fri, 17 Oct 2025 13:03:05 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: Sudeep Holla <sudeep.holla@....com>, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Adam Young <admiyo@...amperecomputing.com>,
 Robbie King <robbiek@...ghtlabs.com>, Huisong Li <lihuisong@...wei.com>,
 Jassi Brar <jassisinghbrar@...il.com>,
 Cristian Marussi <cristian.marussi@....com>
Subject: Re: [PATCH 6/6] mailbox: pcc: Clear any pending responder interrupts
 before enabling it

Tested-by: Adam Young <admiyo@...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@....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;
>