Re: [alsa-devel] regression v4.16 on Nokia N900: sound does not work
From: Andrew F. Davis
Date: Fri Mar 02 2018 - 09:24:35 EST
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..
> 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))
>