linux-kernel - Re: [PATCH v2 2/4] soundwire: core: add device tree support for slave devices

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Date:   Fri, 9 Aug 2019 09:24:45 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        broonie@...nel.org, bgoswami@...eaurora.org, plai@...eaurora.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        lgirdwood@...il.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] soundwire: core: add device tree support for slave
 devices



On 09/08/2019 06:46, Vinod Koul wrote:
>>>> +int sdw_of_find_slaves(struct sdw_bus *bus)
>>>> +{
>>>> +    struct device *dev = bus->dev;
>>>> +    struct device_node *node;
>>>> +
>>>> +    for_each_child_of_node(bus->dev->of_node, node) {
>>>> +        struct sdw_slave_id id;
>>>> +        const char *compat = NULL;
>>>> +        int unique_id, ret;
>>>> +        int ver, mfg_id, part_id, class_id;
>>>> +
>>>> +        compat = of_get_property(node, "compatible", NULL);
>>>> +        if (!compat)
>>>> +            continue;
>>>> +
>>>> +        ret = sscanf(compat, "sdw%x,%x,%x,%x",
>>>> +                 &ver, &mfg_id, &part_id, &class_id);
>>>> +        if (ret != 4) {
>>>> +            dev_err(dev, "Manf ID & Product code not found %s\n",
>>>> +                compat);
>>>> +            continue;
>>>> +        }
>>>> +
>>>> +        ret = of_property_read_u32(node, "sdw-instance-id", &unique_id);
>>>> +        if (ret) {
>>>> +            dev_err(dev, "Instance id not found:%d\n", ret);
>>>> +            continue;
>>> I am confused here.
>>> If you have two identical devices on the same link, isn't this property
>>> required and that should be a real error instead of a continue?
>> Yes, I agree it will be mandatory in such cases.
>>
>> Am okay either way, I dont mind changing it to returning EINVAL in all the
>> cases.
> Do we want to abort? We are in loop scanning for devices so makes sense
> if we do not do that and continue to check next one..

That was my inital plan.
Pierre suggested a better compatible to include instance ID and LinkID 
so this check would be part of the check one before this line.

--srini