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

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

Thanks for taking time to review.

On 08/08/2019 16:00, Pierre-Louis Bossart wrote:
> 
>> @@ -35,6 +36,7 @@ static int sdw_slave_add(struct sdw_bus *bus,
>>       slave->dev.release = sdw_slave_release;
>>       slave->dev.bus = &sdw_bus_type;
>> +    slave->dev.of_node = of_node_get(to_of_node(fwnode));
> 
> shouldn't this protected by
> #if IS_ENABLED(CONFIG_OF) ?
> 
These macros and functions have dummy entries, so it should not be an issue.
I did build soundwire with i386_defconfig with no issues.

>>       slave->bus = bus;
>>       slave->status = SDW_SLAVE_UNATTACHED;
>>       slave->dev_num = 0;
>> @@ -112,3 +114,48 @@ int sdw_acpi_find_slaves(struct sdw_bus *bus)
>>   }
>>   #endif
>> +
>> +/*
>> + * sdw_of_find_slaves() - Find Slave devices in master device tree node
>> + * @bus: SDW bus instance
>> + *
>> + * Scans Master DT node for SDW child Slave devices and registers it.
>> + */
>> +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.

> 
>> +        }
>> +
>> +        id.sdw_version = ver - 0xF;
> 
> maybe a comment in the code would help to make the encoding 
> self-explanatory, as you did in the DT bindings
> 
>    Version number '0x10' represents SoundWire 1.0
>    Version number '0x11' represents SoundWire 1.1

Makes sense, will fix this in next version.
This info is also available in bindings.


--srini
> 
>> +        id.unique_id = unique_id;
>> +        id.mfg_id = mfg_id;
>> +        id.part_id = part_id;
>> +        id.class_id = class_id;
>> +        sdw_slave_add(bus, &id, of_fwnode_handle(node));
>> +    }
>> +    return 0;
>> +}
>>