On Thu, Sep 4, 2014 at 7:38 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, 4 Sep 2014, Anjana V Kumar wrote:
>
>> >> We see that, the three configurations listed in serial driver (CDC
>> >> ACM, CDC OBEX, generic serial) cannot be present together as per the
>> >> current implementation. Is there a specific reason why the
>> >> configuration values were set as 1, 2 and 3 instead of setting all to
>> >> 1?
>> >
>> > well, setting configuration 0 means that you're not selecting any
>> > configuration. Basically you go back to "Addressed" state, so you can't
>> > use configuration 0 for anything, really.
>> >
>>
>> Sorry for not being clear, I am not setting the configuration to 0.
>> The question was, can we set all the three configuration values of CDC
>> ACM, CDC OBEX, and generic serial to 1?
>> Was there any specific reason as to why the configuration values were
>> set as 1,2 and 3. We cannot have all three at the same time according
>> to the current "if, elseif, else" implementation,
>
> No two configurations can have the same bConfigurationValue. If the
> gadget has three different configs then it must have three different
> config values.
>
I agree that no two configurations can have same bConfigurationValue,
but in this case, the implementation is (drivers/usb/gadget/serial.c)
247 if (use_acm) {
248 serial_config_driver.label = "CDC ACM config";
249 serial_config_driver.bConfigurationValue = 2;
250 ...
253 } else if (use_obex) {
254 serial_config_driver.label = "CDC OBEX config";
255 serial_config_driver.bConfigurationValue = 3;
256 ...
259 } else {
260 serial_config_driver.label = "Generic Serial config";
261 serial_config_driver.bConfigurationValue = 1;
262 ...
265 }
In this case we cannot have the three configurations together.
Hence I wanted to confirm if there was any other reason as to why
different numbers were assigned.
> Alan Stern
>
--
Anjana
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