Messages in this thread | | | Date | Fri, 09 Jan 2015 09:48:42 +0100 | From | Clemens Ladisch <> | Subject | Re: [alsa-devel] [PATCH v2] ALSA: usb-audio: Add support for Akai MPC Element USB MIDI controller |
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Paul Bonser wrote: > On 01/08/2015 03:56 PM, Clemens Ladisch wrote: >> Paul Bonser wrote: >>> The Akai MPC Element incorrectly reports its bInterfaceClass as 255, but >>> otherwise implements the USB MIDI spec correctly. >>> >>> This adds a quirks-table.h entry which allows the device to be >>> recognized as a standard USB MIDI device. >>> >>> +++ b/sound/usb/quirks-table.h >>> +{ >>> + /* Akai MPC Element */ >>> + USB_DEVICE(0x09e8, 0x0021), >>> + .driver_info = (unsigned long) & (const struct snd_usb_audio_quirk) { >>> + .ifnum = QUIRK_ANY_INTERFACE, >>> + .type = QUIRK_COMPOSITE, >>> + .data = & (const struct snd_usb_audio_quirk[]) { >>> + { >>> + .ifnum = 0, >>> + .type = QUIRK_IGNORE_INTERFACE >>> + }, >>> + { >>> + .ifnum = 1, >>> + .type = QUIRK_MIDI_STANDARD_INTERFACE >>> + }, >>> + { >>> + .ifnum = -1 >>> + } >>> + } >>> + } >>> +}, >> >> Why a composite quirk? Does a single quirk entry not work? > > A single quirk entry results in an error message in dmesg: > "snd-usb-audio: probe of 3-2:1.0 failed with error -5"
That message is normal for unhandled interfaces.
Does it actually prevent the device from working?
Regards, Clemens
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