linux-kernel - Re: [alsa-devel] [PATCH 08/14] soundwire: Add Slave status handling helpers

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Message-ID: <98f1b39a-b48d-2603-8e9d-88b4f804e2c8@linux.intel.com>
Date:   Wed, 1 Nov 2017 02:49:15 +0530
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vinod.koul@...el.com>, Takashi Iwai <tiwai@...e.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        ALSA <alsa-devel@...a-project.org>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Sudheer Papothi <spapothi@...eaurora.org>, plai@...eaurora.org,
        LKML <linux-kernel@...r.kernel.org>, patches.audio@...el.com,
        Mark <broonie@...nel.org>, srinivas.kandagatla@...aro.org,
        Shreyas NC <shreyas.nc@...el.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        Sagar Dharia <sdharia@...eaurora.org>, alan@...ux.intel.com
Subject: Re: [alsa-devel] [PATCH 08/14] soundwire: Add Slave status handling
 helpers


> 
>>> +		if (found == false) {
>>> +			/* TODO: Park this device in Group 13 */
>>> +			dev_err(bus->dev, "Slave Entry not found");
>>
>> No break here?  Otherwise...
> 
> Thats intentional. We want to still read next device that show up
> 
>>
>>> +		}
>>> +
>>> +	} while (ret == 0);
>>
>> ... the outer loop may go endlessly.
>> This condition doesn't look effective.
> 
> not really. We cant keep reading successfully. At some point all slaves will
> ignore and return ENODATA and we exit. Bus errors will also make it exit
> 
> BUT given that we have seen stuff i am inclined to add a counter, we cant
> have more than 11 device so that's a sane value to use :)

Yep. Keep in mind however that there could be theoretical corner cases: 
if a device is enumerated, loses sync and becomes attached again while 
you deal with others, you'd have more than 11 iterations.