linux-kernel - Re: [RFC PATCH] mailbox: omap-mailbox: Flush out pending msgs before entering suspend

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Message-ID: <CAK4ZnzmKOFYcC8YhZ47DgAp3oDhZmwhQ211u76-UaPYFmz_F+Q@mail.gmail.com>
Date: Wed, 22 Oct 2025 10:45:31 -0300
From: Hiago De Franco <hiagofranco@...il.com>
To: Beleswar Padhi <b-padhi@...com>
Cc: jassisinghbrar@...il.com, linux-kernel@...r.kernel.org, afd@...com, 
	hnagalla@...com, u-kumar1@...com, Hiago De Franco <hiago.franco@...adex.com>
Subject: Re: [RFC PATCH] mailbox: omap-mailbox: Flush out pending msgs before
 entering suspend

On 22.10.2025 15:50, Beleswar Padhi wrote:
> There may be pending messages in the mailbox FIFO that are not consumed
> by the remote processor for various reasons; the remote processor may
> already be powered off or may be in a bad state. Instead of aborting
> suspend because of these pending messages, flush the FIFOs and proceed
> with suspend. Pending messages could also be restored in the resume
> context, but since remote processors are typically rebooted during
> suspend/resume today, there is no point in restoring stale messages.
>
> Signed-off-by: Beleswar Padhi <b-padhi@...com>

Thanks for your patch, I tested it on Verdin AM62 and it is working
fine.

Please add the following tags:

Closes: https://lore.kernel.org/all/sid7gtg5vay5qgicsl6smnzwg5mnneoa35cempt5ddwjvedaio@hzsgcx6oo74l/
Fixes: 1d6161617c10 ("arm64: dts: ti: k3-am62-ti-ipc-firmware:
Refactor IPC cfg into new dtsi")

With that,

Tested-by: Hiago De Franco <hiago.franco@...adex.com> # Verdin AM62

Best regards,
Hiago.

> ---
>  drivers/mailbox/omap-mailbox.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
> index 680243751d62..5e6373911630 100644
> --- a/drivers/mailbox/omap-mailbox.c
> +++ b/drivers/mailbox/omap-mailbox.c
> @@ -341,13 +341,10 @@ static int omap_mbox_suspend(struct device *dev)
>      if (pm_runtime_status_suspended(dev))
>          return 0;
>
> -    for (fifo = 0; fifo < mdev->num_fifos; fifo++) {
> -        if (mbox_read_reg(mdev, MAILBOX_MSGSTATUS(fifo))) {
> -            dev_err(mdev->dev, "fifo %d has unexpected unread messages\n",
> -                fifo);
> -            return -EBUSY;
> -        }
> -    }
> +    /* Flush out pending mbox messages before entering suspend */
> +    for (fifo = 0; fifo < mdev->num_fifos; fifo++)
> +        while (mbox_read_reg(mdev, MAILBOX_MSGSTATUS(fifo)) != 0)
> +            mbox_read_reg(mdev, MAILBOX_MESSAGE(fifo));
>
>      for (usr = 0; usr < mdev->num_users; usr++) {
>          reg = MAILBOX_IRQENABLE(mdev->intr_type, usr);
> --
> 2.34.1
>

On Wed, Oct 22, 2025 at 7:20 AM Beleswar Padhi <b-padhi@...com> wrote:
>
> There may be pending messages in the mailbox FIFO that are not consumed
> by the remote processor for various reasons; the remote processor may
> already be powered off or may be in a bad state. Instead of aborting
> suspend because of these pending messages, flush the FIFOs and proceed
> with suspend. Pending messages could also be restored in the resume
> context, but since remote processors are typically rebooted during
> suspend/resume today, there is no point in restoring stale messages.
>
> Signed-off-by: Beleswar Padhi <b-padhi@...com>
> ---
>  drivers/mailbox/omap-mailbox.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
> index 680243751d62..5e6373911630 100644
> --- a/drivers/mailbox/omap-mailbox.c
> +++ b/drivers/mailbox/omap-mailbox.c
> @@ -341,13 +341,10 @@ static int omap_mbox_suspend(struct device *dev)
>         if (pm_runtime_status_suspended(dev))
>                 return 0;
>
> -       for (fifo = 0; fifo < mdev->num_fifos; fifo++) {
> -               if (mbox_read_reg(mdev, MAILBOX_MSGSTATUS(fifo))) {
> -                       dev_err(mdev->dev, "fifo %d has unexpected unread messages\n",
> -                               fifo);
> -                       return -EBUSY;
> -               }
> -       }
> +       /* Flush out pending mbox messages before entering suspend */
> +       for (fifo = 0; fifo < mdev->num_fifos; fifo++)
> +               while (mbox_read_reg(mdev, MAILBOX_MSGSTATUS(fifo)) != 0)
> +                       mbox_read_reg(mdev, MAILBOX_MESSAGE(fifo));
>
>         for (usr = 0; usr < mdev->num_users; usr++) {
>                 reg = MAILBOX_IRQENABLE(mdev->intr_type, usr);
> --
> 2.34.1
>