linux-kernel - Re: [PATCH 09/13] soundwire: intel: add CLK_STOP_BUS

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Message-ID: <8aac898f-92d3-c907-ebb8-4642a618645b@linux.intel.com>
Date:   Mon, 17 Aug 2020 09:30:02 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        rander.wang@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
        hui.wang@...onical.com, sanyog.r.kale@...el.com,
        slawomir.blauciak@...el.com, mengdong.lin@...el.com,
        bard.liao@...el.com
Subject: Re: [PATCH 09/13] soundwire: intel: add CLK_STOP_BUS_RESET support




>> +	} else if (clock_stop_quirks & SDW_INTEL_CLK_STOP_BUS_RESET) {
>> +		ret = sdw_cdns_clock_stop(cdns, true);
>> +		if (ret < 0) {
>> +			dev_err(dev, "cannot enable clock stop on suspend\n");
>> +			return ret;
>> +		}
>> +
>> +		ret = sdw_cdns_enable_interrupt(cdns, false);
>> +		if (ret < 0) {
>> +			dev_err(dev, "cannot disable interrupts on suspend\n");
>> +			return ret;
>> +		}
>> +
>> +		ret = intel_link_power_down(sdw);
>> +		if (ret) {
>> +			dev_err(dev, "Link power down failed: %d", ret);
>> +			return ret;
>> +		}
> 
> no cleanup on all the error cases here?

See above the 'else if' test, the clock stop on suspend will be followed 
by a bus reset on resume. this is essentially a complete bus restart.

The only open here is whether we should actually return an error while 
suspending, or just log the error and squelch it. We decided to return 
the status so that the pm_runtime suspend does not proceed: the state 
remains active which is easier to detect than a single line in a dmesg log.