[alsa-devel] [PATCH] usb: add USB_QUIRK_RESET_RESUME for M-Audio 49

[Clemens Ladisch]

Takashi Iwai wrote:
> Clemens Ladisch wrote:
>> Takashi Iwai wrote:
>>> Clemens Ladisch wrote:
>>>> I'm working on a fix that adds proper power management for input ports,
>>>> but this requires the driver to be reorganized a little ...
>>>
>>> Doesn't a simple patch like below work?
>>
>>> +static int substream_open(struct snd_rawmidi_substream *substream, int open)
>>>  {
>>> +	if (open && umidi->opened++ == 0) {
>>> +		err = usb_autopm_get_interface(umidi->iface);
>>>
>>>  static int snd_usbmidi_input_open(struct snd_rawmidi_substream *substream)
>>>  {
>>> +	return substream_open(substream, 1);
>>
>> No, because the input URBs are submitted before the userspace device is
>> opened.
>
> Ah, right.  What's the reason of submitting input urbs for the all
> time from the beginning?  For loopback?

For not needing to count open input ports.

> If it has to be running, the easiest fix would be the patch like
> below.  This will turn off the autopm essentially, but better than
> breakage.
>
> @@ -2074,6 +2077,8 @@ static void snd_usbmidi_input_start_ep(struct snd_usb_midi_in_endpoint* ep)
>
> +	ep->autopm_reference =
> +		usb_autopm_get_interface(ep->umidi->iface) >= 0;

usb_autopm_get_interface() cannot be called from the USB probe callback.


Regards,
Clemens