linux-kernel - Re: [alsa-devel] [RFC PATCH 15/40] soundwire: cadence_master: handle multiple status reports per Slave

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Date:   Fri, 26 Jul 2019 09:09:56 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Guennadi Liakhovetski <guennadi.liakhovetski@...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 15/40] soundwire: cadence_master: handle
 multiple status reports per Slave


>> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
>> index 889fa2cd49ae..25d5c7267c15 100644
>> --- a/drivers/soundwire/cadence_master.c
>> +++ b/drivers/soundwire/cadence_master.c
>> @@ -643,13 +643,35 @@ static int cdns_update_slave_status(struct sdw_cdns *cdns,
>>   
>>   		/* first check if Slave reported multiple status */
>>   		if (set_status > 1) {
>> +			u32 val;
>> +
>>   			dev_warn_ratelimited(cdns->dev,
>> -					     "Slave reported multiple Status: %d\n",
>> -					     mask);
>> -			/*
>> -			 * TODO: we need to reread the status here by
>> -			 * issuing a PING cmd
>> -			 */
>> +					     "Slave %d reported multiple Status: %d\n",
>> +					     i, mask);
>> +
>> +			/* re-check latest status extracted from PING commands */
>> +			val = cdns_readl(cdns, CDNS_MCP_SLAVE_STAT);
>> +			val >>= (i * 2);
> 
> Superfluous parentheses.

Humm, I don't know my left from my right and I can't remember operator 
precedence, so i'd rather make it explicit...

> 
>> +
>> +			switch (val & 0x3) {
>> +			case 0:
>> +				status[i] = SDW_SLAVE_UNATTACHED;
>> +				break;
>> +			case 1:
>> +				status[i] = SDW_SLAVE_ATTACHED;
>> +				break;
>> +			case 2:
>> +				status[i] = SDW_SLAVE_ALERT;
>> +				break;
>> +			default:
> 
> There aren't many values left for the "default" case :-) But I'm not sure whether
> any of
> 
> +			case 3:
> 
> or
> 
> +			case 3:
> +			default:
> 
> would improve readability.
> 
> Thanks
> Guennadi
> 
>> +				status[i] = SDW_SLAVE_RESERVED;
>> +				break;

Yes, those defaults are annoying. Some tools complain so I tend to leave 
them.