linux-kernel - Re: [PATCH 2/3] soundwire: qcom: add auto enumeration support

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Message-ID: <a9129fe5-c505-920f-d3d4-85282ce83120@linaro.org>
Date:   Fri, 5 Mar 2021 16:57:41 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        vkoul@...nel.org
Cc:     sanyog.r.kale@...el.com, yung-chuan.liao@...ux.intel.com,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH 2/3] soundwire: qcom: add auto enumeration support



On 05/03/2021 16:19, Pierre-Louis Bossart wrote:
>>>
>>>
>>> The question is: what happens if that device is NOT described in the 
>>> Device Tree data? The loop over bus->slaves will not find this device 
>>> by comparing with known devID values, so the set_bit(i, 
>>> bus->assigned) will not happen.
>>
>> yes, that is true, There is no way we can assign a dev_number to the 
>> device which is not enumerated on the bus!
>>
>> Am sure this is the same behavior with soundwire core too, atleast 
>> form the code I can see it sets the assigned bit for only the devices 
>> that are enumerated on the bus! Not all the devices specified in DT!
>> Unless I missed something!
> 
> I am talking about the other way around, where a device is present and 
> enumerated on the bus but not listed in DT. In that case the hardware 
> did assign a device number but bus->assigned will not be set.

thanks for your patience!

Ah, I understand it now!, yes that part is missing!

adding Something like what core does in qcom driver should fix it!

if (!found) {
	sdw_slave_add(bus, &id, NULL);
	dev_err(bus->dev, "Slave Entry not found\n");
}

--srini