Re: [PATCH 1/2] Input: i8042 - Prevent intermixing i8042 commands

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Thu, Aug 27, 2020 at 11:12 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Thu, Aug 27, 2020 at 10:52 PM Raul E Rangel <rrangel@chromium.org> wrote:

...

> > +       mutex_lock(&i8042_mutex);
> > +
> >         spin_lock_irqsave(&i8042_lock, flags);
> >         retval = __i8042_command(param, command);
> >         spin_unlock_irqrestore(&i8042_lock, flags);
> >
> > +        mutex_unlock(&i8042_mutex);
>
> Question 1. Why do you need mutex at all in the above situation? Spin
> lock isn't enough?
>
> ...
>
> > -       i8042_lock_chip();
> > -
> >         if (value == LED_OFF)
> >                 i8042_command(NULL, CLEVO_MAIL_LED_OFF);
> >         else if (value <= LED_HALF)
> >                 i8042_command(NULL, CLEVO_MAIL_LED_BLINK_0_5HZ);
> >         else
> >                 i8042_command(NULL, CLEVO_MAIL_LED_BLINK_1HZ);
> > -
> > -       i8042_unlock_chip();
> > -
>
> Now, these three commands are not considered as a transaction (no
> atomicity). That's why your patch is wrong.

Ah, I didn't pay attention that this is one command call. But still Q1 is valid.

-- 
With Best Regards,
Andy Shevchenko