On Mon, Jun 22, 2020 at 10:42:38AM -0500, Pierre-Louis Bossart wrote:
> The mainline code currently prevents modules from being removed.
>
> The BE dailink .init() function calls devm_gpiod_get() using the codec
> component device as argument. When the machine driver is removed, the
> references to the gpiod are not released, and it's not possible to
> remove the codec driver module - which is the only entity which could
> free the gpiod.
>
> This conceptual deadlock can be avoided by invoking gpiod_get() in the
> .init() callback, and calling gpiod_put() in the exit() callback.
>
> Tested on SAMUS Chromebook with SOF driver.
> +static void bdw_rt5677_exit(struct snd_soc_pcm_runtime *rtd)
> +{
> + struct bdw_rt5677_priv *bdw_rt5677 =
> + snd_soc_card_get_drvdata(rtd->card);
> +
> + /*
> + * The .exit() can be reached without going through the .init()
> + * so explicitly test if the gpiod is valid
> + */
> + if (!IS_ERR_OR_NULL(bdw_rt5677->gpio_hp_en))
_OR_NULL is redundant. gpiod_put() is explicitly NULL-aware.
IS_ERR() I suppose can be avoided by using gpiod_get_optional(), if it suits the case.
Otherwise it would be questionable why we got error pointer value on ->exit().
> + gpiod_put(bdw_rt5677->gpio_hp_en);
> +}
--
With Best Regards,
Andy Shevchenko
