[alsa-devel] [PATCH] soundwire: fix pm_runtime_get_sync return code checks

[Pierre-Louis Bossart]

On 4/5/19 2:26 AM, Jan Kotas wrote:
> When PM is disabled it returns -EACCES, which is currently
> threated as an error, and prevents accessing the slave's
> registers.
>
> This patch ignores the -EACCES return value from
> pm_runtime_get_sync() to let the SoundWire work in systems
> without runtime PM.
>
> Signed-off-by: Jan Kotas <jank at cadence.com>
> ---
>   drivers/soundwire/bus.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> index 1cbfedfc2..6567ff439 100644
> --- a/drivers/soundwire/bus.c
> +++ b/drivers/soundwire/bus.c
> @@ -328,7 +328,7 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
>   		return ret;
>   
>   	ret = pm_runtime_get_sync(slave->bus->dev);
> -	if (ret < 0)
> +	if (ret < 0 && ret != -EACCES)

There was a patch submitted on 3/28 by Srinivas Kandagatla who suggested an alternate solution for exactly the same code.

+	if (pm_runtime_enabled(slave->bus->dev)) {
+		ret = pm_runtime_get_sync(slave->bus->dev);
+		if (ret < 0)
+			return ret;

I am far from an expert on pm_runtime but Srinivas' solution looks more elegant to me.
-Pierre