Re: [PATCH v4 5/7] usb: gadget: f_midi: set altsettings only for MIDIStreaming interface

[Felipe Tonello <eu@felipetonello.com>]

Hi Robert,

On Mon, Oct 26, 2015 at 10:30 PM, Robert Baldyga
<r.baldyga@hackerion.com> wrote:
> On 10/26/2015 05:55 PM, Felipe F. Tonello wrote:
>> This avoids duplication of USB requests for OUT endpoint and
>> re-enabling endpoints.
>>
>> Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
>> ---
>>  drivers/usb/gadget/function/f_midi.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
>> index 0e9cdeb..a617df3 100644
>> --- a/drivers/usb/gadget/function/f_midi.c
>> +++ b/drivers/usb/gadget/function/f_midi.c
>> @@ -323,6 +323,10 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>>       unsigned i;
>>       int err;
>>
>> +     /* We don't care if it is not MIDIStreaming interface */
>> +     if (intf != ms_interface_desc.bInterfaceNumber)
>> +             return 0;
>> +
>
> These global descriptors are overwritten in bind() of each instance of
> f_midi, so you have no guarantee that your bInterfaceNumber is correct
> for your current instance. Instead you should store value obtained from
> usb_interface_id() during bind().

Ok.

But then this interface descriptors shouldn't be global static,
because they will always reflect the latest bind() only. Right?

>
>>       err = f_midi_start_ep(midi, f, midi->in_ep);
>>       if (err)
>>               return err;
>>

Felipe