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

From: Pavel Machek
Date: Fri Mar 02 2018 - 06:10:53 EST


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)
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))

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

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