Re: [char-misc v3] mei: me: reduce the scope on unexpected reset

[Rafael J. Wysocki]

On Thu, Mar 26, 2026 at 4:14 PM Alexander Usyskin
<alexander.usyskin@xxxxxxxxx> wrote:
>
> After commit 2cedb296988c ("mei: me: trigger link reset if hw ready is unexpected")
> some devices started to show long resume times (5-7 seconds).
> This happens as mei falsely detects unready hardware,
> starts parallel link reset flow and triggers link reset timeouts
> in the resume callback.
>
> Address it by performing detection of unready hardware only
> when driver is in the ENABLED state instead of blacklisting
> states as done in the original patch.
>
> Reported-by: Todd Brandt <todd.e.brandt@xxxxxxxxxxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221023
> Tested-by: Todd Brandt <todd.e.brandt@xxxxxxxxxxxxxxx>
> Fixes: 2cedb296988c ("mei: me: trigger link reset if hw ready is unexpected")
> Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
> ---
>
> V3: reword commit message, add Rafael and PM list
>
> V2: rebase over v7.0-rc4
>
>  drivers/misc/mei/hw-me.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
> index d4612c659784..1e4a41ac428f 100644
> --- a/drivers/misc/mei/hw-me.c
> +++ b/drivers/misc/mei/hw-me.c
> @@ -1337,19 +1337,13 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
>         /*  check if we need to start the dev */
>         if (!mei_host_is_ready(dev)) {
>                 if (mei_hw_is_ready(dev)) {
> -                       /* synchronized by dev mutex */

I think that the comment above is still valid, isn't it?  If so, why remove it?

> -                       if (waitqueue_active(&dev->wait_hw_ready)) {
> -                               dev_dbg(&dev->dev, "we need to start the dev.\n");
> -                               dev->recvd_hw_ready = true;
> -                               wake_up(&dev->wait_hw_ready);
> -                       } else if (dev->dev_state != MEI_DEV_UNINITIALIZED &&
> -                                  dev->dev_state != MEI_DEV_POWERING_DOWN &&
> -                                  dev->dev_state != MEI_DEV_POWER_DOWN) {
> +                       if (dev->dev_state == MEI_DEV_ENABLED) {
>                                 dev_dbg(&dev->dev, "Force link reset.\n");
>                                 schedule_work(&dev->reset_work);
>                         } else {

Isn't the waitqueue_active() check needed any more?

> -                               dev_dbg(&dev->dev, "Ignore this interrupt in state = %d\n",
> -                                       dev->dev_state);
> +                               dev_dbg(&dev->dev, "we need to start the dev.\n");
> +                               dev->recvd_hw_ready = true;
> +                               wake_up(&dev->wait_hw_ready);
>                         }
>                 } else {
>                         dev_dbg(&dev->dev, "Spurious Interrupt\n");
> --