linux-kernel - Re: [alsa-devel] [PATCH 2/6] soundwire: cadence_master: add hw

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Message-ID: <71411347-93cf-2617-4edd-f6b401fe7a9b@linux.intel.com>
Date:   Wed, 4 Sep 2019 08:18:45 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>
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,
        slawomir.blauciak@...el.com, Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [alsa-devel] [PATCH 2/6] soundwire: cadence_master: add hw_reset
 capability in debugfs

On 9/4/19 2:13 AM, Vinod Koul wrote:
> On 13-08-19, 16:32, Pierre-Louis Bossart wrote:
>> Provide debugfs capability to kick link and devices into hard-reset
>> (as defined by MIPI). This capability is really useful when some
>> devices are no longer responsive and/or to check the software handling
>> of resynchronization.
>>
>> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
>> ---
>>   drivers/soundwire/cadence_master.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
>> index 046622e4b264..bd58d80ff636 100644
>> --- a/drivers/soundwire/cadence_master.c
>> +++ b/drivers/soundwire/cadence_master.c
>> @@ -340,6 +340,23 @@ static int cdns_reg_show(struct seq_file *s, void *data)
>>   }
>>   DEFINE_SHOW_ATTRIBUTE(cdns_reg);
>>   
>> +static int cdns_hw_reset(void *data, u64 value)
>> +{
>> +	struct sdw_cdns *cdns = data;
>> +	int ret;
>> +
>> +	if (value != 1)
>> +		return 0;
> 
> Should this not be EINVAL to indicate invalid value passed?

Maybe. I must admit I don't know what -EINVAL would do, this is used for 
debugfs so it's not clear to me if the user will see a difference?

> 
>> +
>> +	ret = sdw_cdns_exit_reset(cdns);
>> +
>> +	dev_dbg(cdns->dev, "link hw_reset done: %d\n", ret);
>> +
>> +	return ret;
>> +}
>> +
>> +DEFINE_DEBUGFS_ATTRIBUTE(cdns_hw_reset_fops, NULL, cdns_hw_reset, "%llu\n");
>> +
>>   /**
>>    * sdw_cdns_debugfs_init() - Cadence debugfs init
>>    * @cdns: Cadence instance
>> @@ -348,6 +365,9 @@ DEFINE_SHOW_ATTRIBUTE(cdns_reg);
>>   void sdw_cdns_debugfs_init(struct sdw_cdns *cdns, struct dentry *root)
>>   {
>>   	debugfs_create_file("cdns-registers", 0400, root, cdns, &cdns_reg_fops);
>> +
>> +	debugfs_create_file("cdns-hw-reset", 0200, root, cdns,
>> +			    &cdns_hw_reset_fops);
>>   }
>>   EXPORT_SYMBOL_GPL(sdw_cdns_debugfs_init);
>>   
>> -- 
>> 2.20.1
>