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

[Usyskin, Alexander]

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

The fix simplifies original patch as in MEI_DEV_ENABLED state there will be no active waitqueue.
This also removes need for comment about waitqueue synchronization.

- - 
Thanks,
Sasha