Re: [alsa-devel] regression v4.16 on Nokia N900: sound does not work

From: Pavel Machek
Date: Fri Mar 02 2018 - 11:53:30 EST


On Fri 2018-03-02 08:22:52, Andrew F. Davis wrote:
> On 03/02/2018 05:10 AM, Pavel Machek wrote:
> > Hi!
> >
> >>> If this is taking longer to fix, should c85823390215 be reverted in
> >>> the meantime? It does not seem particulary important/urgent...
> >>
> >> No patience between the v4.16 release candidates eh ;)
> >>
> >> commit 6662ae6af82df10259a70c7569b4c12ea7f3ba93
> >> ("gpiolib: Keep returning EPROBE_DEFER when we should")
> >>
> >> and
> >>
> >> commit ce27fb2c56db6ccfe8099343bb4afdab15e77e7b
> >> ("gpio: Handle deferred probing in of_find_gpio() properly")
> >>
> >> that are both in Torvalds' tree since yesterday should be fixing
> >> this, I think? Did you try just using the upstream HEAD?
> >
> > Ok, so this code looks pretty crazy to me: I tried removing the
> > "of_find_spi_gpio" part, and audio started working.
> >
> > What is going on with the ()s around == s? You made me look up C
> > operator precedence.
> >
> > Hmm, and it is also wrong, right? It turns any error code into ENOENT,
> > as it tries to do the "special handling".
> >
> > *
> > * This means we don't need to look any further for
> > * alternate name conventions, and we should really
> > * preserve the return code for our user to be able to
> > * retry probing later.
> > */
> > if (IS_ERR(desc) && PTR_ERR(desc) == -EPROBE_DEFER)
> > return desc;
> >
> > if (!IS_ERR(desc) || (PTR_ERR(desc) != -ENOENT))
> > break;
> > }
> >
> > /* Special handling for SPI GPIOs if used */
> > if (IS_ERR(desc))
> > desc = of_find_spi_gpio(dev, con_id, &of_flags);
> >
> > /* Special handling for regulator GPIOs if used */
> > if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
> > desc = of_find_regulator_gpio(dev, con_id, &of_flags);
> >
> > Something like this?
> >
> > diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> > index 84e5a9d..f0fab26 100644
> > --- a/drivers/gpio/gpiolib-of.c
> > +++ b/drivers/gpio/gpiolib-of.c
> > @@ -241,29 +241,17 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
> >
> > desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
> > &of_flags);
> > - /*
> > - * -EPROBE_DEFER in our case means that we found a
> > - * valid GPIO property, but no controller has been
> > - * registered so far.
> > - *
> > - * This means we don't need to look any further for
> > - * alternate name conventions, and we should really
> > - * preserve the return code for our user to be able to
> > - * retry probing later.
> > - */
> > - if (IS_ERR(desc) && PTR_ERR(desc) == -EPROBE_DEFER)
> > - return desc;
> >
> > - if (!IS_ERR(desc) || (PTR_ERR(desc) != -ENOENT))
> > + if (!IS_ERR(desc) || PTR_ERR(desc) != -ENOENT)
>
>
> I rather like the () so one doesn't always have to look up C operator
> precedence to verify..

Well, Ok, but then the ()s should be at the other ifs nearby, too. See?

>
> > break;
> > }
> >
> > /* Special handling for SPI GPIOs if used */
> > - if (IS_ERR(desc))
> > + if (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
> > desc = of_find_spi_gpio(dev, con_id, &of_flags);
> >
> > /* Special handling for regulator GPIOs if used */
> > - if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
> > + if (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
> > desc = of_find_regulator_gpio(dev, con_id, &of_flags);
> >
> > if (IS_ERR(desc))
> >
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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