On Sat, 09 Apr 2016 11:16:59 +0200,
Daniel Mack wrote:
>
> On 04/09/2016 10:52 AM, Takashi Iwai wrote:
> > 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 :)
>
> I had something like that before but opted for the more readable
> version. But you're right. I'll add a comment and do it your way.
Oh no, sorry, I wasn't clear: I meant that my version is worse in the
end, and I prefer your first version, just for simplicity.
Takashi
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