On Fri, 08 Apr 2016 19:52:02 +0200,
Daniel Mack wrote:
>
> miniDSP USBStreamer UAC2 devices send clock validity changes with the
> control field set to zero. The current interrupt handler ignores all
> packets if the control field does not match the mixer element's, but
> it really should only do that in case that field is needed to
> distinguish multiple elements with the same ID.
>
> This patch implements a logic that lets notifications packets pass
> if the element ID is unique for a given device.
>
> Signed-off-by: Daniel Mack <daniel@xxxxxxxxxx>
> ---
> sound/usb/mixer.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 973274b..aa6f16e 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -2371,6 +2371,7 @@ static void snd_usb_mixer_interrupt_v2(struct usb_mixer_interface *mixer,
> __u8 unitid = (index >> 8) & 0xff;
> __u8 control = (value >> 8) & 0xff;
> __u8 channel = value & 0xff;
> + unsigned int count = 0;
>
> if (channel >= MAX_CHANNELS) {
> usb_audio_dbg(mixer->chip,
> @@ -2379,6 +2380,12 @@ static void snd_usb_mixer_interrupt_v2(struct usb_mixer_interface *mixer,
> return;
> }
>
> + for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem)
> + count++;
> +
> + if (count == 0)
> + return;
> +
> for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem) {
> struct usb_mixer_elem_info *info;
>
> @@ -2386,7 +2393,7 @@ static void snd_usb_mixer_interrupt_v2(struct usb_mixer_interface *mixer,
> continue;
>
> info = (struct usb_mixer_elem_info *)list;
> - if (info->control != control)
> + if (count > 1 && info->control != control)
> continue;
Just for checking count=0 and count=1, we need no loop to count
beforehand.
if (info->control != control &&
(list != mixer->id_elems[unit] ||
list->list_next_id_elem))
continue;
But, this doesn't look better and is more harder to understand, so I'm
not willing to sell it :)
thanks,
Takashi
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