linux-kernel - Re: [alsa-devel] [RFC PATCH 17/40] soundwire: bus: use runtime_pm_get

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Message-ID: <716D5D19-D494-4F4E-9180-24CB5A575648@global.cadence.com>
Date:   Fri, 26 Jul 2019 07:47:04 +0000
From:   Jan Kotas <jank@...ence.com>
To:     Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
CC:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "tiwai@...e.de" <tiwai@...e.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Vinod Koul <vkoul@...nel.org>, Mark Brown <broonie@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Jan Kotas <jank@...ence.com>,
        "slawomir.blauciak@...el.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

Hello,

I while back I proposed a patch for this, but it went nowhere.

https://patchwork.kernel.org/patch/10887405/
Maybe something similar can be implemented?

Jan

> On 26 Jul 2019, at 09:39, Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com> wrote:
> 
> EXTERNAL MAIL
> 
> 
> 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
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