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

[Clemens Ladisch <clemens@ladisch.de>]

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