linux-kernel - Re: [PATCH 2/6] mailbox: pcc: Wire up ->last_tx

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: <6d4b85ce-de35-4a38-92ff-34b2caec66d0@huawei.com>
Date: Mon, 20 Oct 2025 12:01:54 +0800
From: "lihuisong (C)" <lihuisong@...wei.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>, Jassi Brar <jassisinghbrar@...il.com>, "Cristian
 Marussi" <cristian.marussi@....com>
Subject: Re: [PATCH 2/6] mailbox: pcc: Wire up ->last_tx_done() for PCC
 channels


在 2025/10/17 3:08, Sudeep Holla 写道:
> Some PCC users poll for completion between transfers and benefit from
> the knowledge of previous Tx completion check through the mailbox
> framework's ->last_tx_done() op.
>
> Hook up the last_tx_done callback in the PCC mailbox driver so the mailbox
> framework can correctly query the completion status of the last transmitted
> message. This aligns PCC with other controllers that already implement such
> last_tx_done status query.
>
> No functional change unless callers use ->last_tx_done(). Normal Tx and
> IRQ paths are unchanged. This change just improves synchronization and
> avoids unnecessary timeouts for non-interrupt driven channels by ensuring
> correct completion detection for PCC channels that don’t rely on interrupts.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/mailbox/pcc.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index f6714c233f5a..2b690c268cf0 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -445,6 +445,13 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
>   	return ret;
>   }
>   
> +static bool pcc_last_tx_done(struct mbox_chan *chan)
> +{
> +	struct pcc_chan_info *pchan = chan->con_priv;
> +
The last_tx_done() is used on the condition that txdone_poll  is true 
and txdone_irq is false.
So how about add WARN_ON() for this in this API?
> +	return pcc_mbox_cmd_complete_check(pchan);
The pcc_mbox_cmd_complete_check() works on type 3/4.
I'm not sure if we need to add some comments or do some other something 
for this.
> +}
> +
>   /**
>    * pcc_startup - Called from Mailbox Controller code. Used here
>    *		to request the interrupt.
> @@ -490,6 +497,7 @@ 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,
>   };
>   
>   /**
>