linux-kernel - Re: [PATCH v30 1/3] mailbox: pcc: Type3 Buffer handles ACK IRQ

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <99aa7b2a-e772-4a93-a724-708e8e0a21ed@amperemail.onmicrosoft.com>
Date: Fri, 17 Oct 2025 12:08:07 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: Adam Young <admiyo@...amperecomputing.com>,
 Sudeep Holla <sudeep.holla@....com>, Jassi Brar <jassisinghbrar@...il.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 Jeremy Kerr <jk@...econstruct.com.au>,
 Matt Johnston <matt@...econstruct.com.au>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Huisong Li <lihuisong@...wei.com>
Subject: Re: [PATCH v30 1/3] mailbox: pcc: Type3 Buffer handles ACK IRQ

This is obsoleted/duplicated by Sudeep's patch.  I am going to rebase on 
his patch series.

On 10/16/25 17:02, Adam Young wrote:
> The PCC protocol type 3 requests include a field that indicates that the
> recipient should trigger an interrupt once the message has been read
> from the buffer. The sender uses this interrupt to know that a
> transmission is complete, and it is safe to send additional messages.
>
> Signed-off-by: Adam Young <admiyo@...amperecomputing.com>
>
> mailbox/pcc extended memory helper functions
> ---
>   drivers/mailbox/pcc.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index f6714c233f5a..978a7b674946 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -306,6 +306,18 @@ static void pcc_chan_acknowledge(struct pcc_chan_info *pchan)
>   		pcc_chan_reg_read_modify_write(&pchan->db);
>   }
>   
> +static bool pcc_last_tx_done(struct mbox_chan *chan)
> +{
> +	struct pcc_chan_info *pchan = chan->con_priv;
> +	u64 val;
> +
> +	pcc_chan_reg_read(&pchan->cmd_complete, &val);
> +	if (!val)
> +		return false;
> +	else
> +		return true;
> +}
> +
>   /**
>    * pcc_mbox_irq - PCC mailbox interrupt handler
>    * @irq:	interrupt number
> @@ -340,6 +352,14 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
>   	 * required to avoid any possible race in updatation of this flag.
>   	 */
>   	pchan->chan_in_use = false;
> +
> +	/**
> +	 * The remote side sent an ack.
> +	 */
> +	if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE &&
> +	    chan->active_req)
> +		mbox_chan_txdone(chan, 0);
> +
>   	mbox_chan_received_data(chan, NULL);
>   
>   	pcc_chan_acknowledge(pchan);
> @@ -490,6 +510,7 @@ static const struct mbox_chan_ops pcc_chan_ops = {
>   	.send_data = pcc_send_data,
>   	.startup = pcc_startup,
>   	.shutdown = pcc_shutdown,
> +	.last_tx_done = pcc_last_tx_done,
>   };
>   
>   /**