Re: [alsa-devel] [PATCH 1/1] ALSA: usb-audio: add support for Akai MPD16

Krzysztof Foltman wrote:

• • AKAI MPD16 protocol: one or more chunks consisting of first byte of
• • (0x20 | msg_len) and then a MIDI message (msg_len bytes long)
• • Messages sent:
• • 21 FE (active sense)
• • 23 90 xx xx (note on)
• • 23 Ax xx xx (polyphonic pressure)
• • 23 Bx xx xx (control change)
• */

+static void snd_usbmidi_akai_input(struct snd_usb_midi_in_endpoint *ep,

• 		   uint8_t *buffer, int buffer_length)
  

+{

• unsigned int pos = 0;
• while (pos < (unsigned)buffer_length && (buffer[pos] & 0xF8) == 0x20) {

• int msg_len = buffer[pos] & 0x0f;
  

• snd_usbmidi_input_data(ep, 0, &buffer[pos + 1], msg_len);
  

This might overflow if the buffer ends with a 2x byte.

+static struct usb_protocol_ops snd_usbmidi_akai_ops = {

• .input = snd_usbmidi_akai_input,
• .output = snd_usbmidi_standard_output,
• .output_packet = snd_usbmidi_output_standard_packet,

Assuming that this device doesn't have any output ports, please add a comment that this isn't the actual output protocol.

checkpatch.pl also complains about the use of space after the ampersand in quirks-table.h, where it seems to be a common practice.

I'd value consistency over some stupid script, but this issue isn't important enough to worry over.

Overall, the patch looks fine.

Regards, Clemens