linux-kernel - Re: [alsa-devel] [RFC PATCH 17/40] soundwire: bus: use runtime_pm_get_sync/pm when enabled

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Message-ID: <20190726073931.GE16003@ubuntu>
Date:   Fri, 26 Jul 2019 09:39:32 +0200
From:   Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, tiwai@...e.de,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        vkoul@...nel.org, broonie@...nel.org,
        srinivas.kandagatla@...aro.org, jank@...ence.com,
        slawomir.blauciak@...el.com, Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [alsa-devel] [RFC PATCH 17/40] soundwire: bus: use
 runtime_pm_get_sync/pm when enabled

Hi Pierre,

I might be wrong but this doesn't seem right to me. (Supposedly) all RT-PM
functions check for "enabled" internally. The only thing that can happen is
that if RT-PM isn't enabled some of those functions will return an error.
So, in those cases where the return value of RT-PM functions isn't checked,
I don't think you need to do anything. Where it is checked maybe do

+	if (ret < 0 && pm_runtime_enabled(slave->bus->dev))

Thanks
Guennadi

On Thu, Jul 25, 2019 at 06:40:09PM -0500, Pierre-Louis Bossart wrote:
> Not all platforms support runtime_pm for now, let's use runtime_pm
> only when enabled.
> 
> Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/bus.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> index 5ad4109dc72f..0a45dc5713df 100644
> --- a/drivers/soundwire/bus.c
> +++ b/drivers/soundwire/bus.c
> @@ -332,12 +332,16 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = pm_runtime_get_sync(slave->bus->dev);
> -	if (ret < 0)
> -		return ret;
> +	if (pm_runtime_enabled(slave->bus->dev)) {
> +		ret = pm_runtime_get_sync(slave->bus->dev);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	ret = sdw_transfer(slave->bus, &msg);
> -	pm_runtime_put(slave->bus->dev);
> +
> +	if (pm_runtime_enabled(slave->bus->dev))
> +		pm_runtime_put(slave->bus->dev);
>  
>  	return ret;
>  }
> @@ -359,13 +363,16 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
>  			   slave->dev_num, SDW_MSG_FLAG_WRITE, val);
>  	if (ret < 0)
>  		return ret;
> -
> -	ret = pm_runtime_get_sync(slave->bus->dev);
> -	if (ret < 0)
> -		return ret;
> +	if (pm_runtime_enabled(slave->bus->dev)) {
> +		ret = pm_runtime_get_sync(slave->bus->dev);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	ret = sdw_transfer(slave->bus, &msg);
> -	pm_runtime_put(slave->bus->dev);
> +
> +	if (pm_runtime_enabled(slave->bus->dev))
> +		pm_runtime_put(slave->bus->dev);
>  
>  	return ret;
>  }
> -- 
> 2.20.1
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@...a-project.org
> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel

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