Commit c55f5692 authored by Vasily Khoruzhick's avatar Vasily Khoruzhick Committed by Takashi Iwai
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ALSA: line6: Add poll callback for hwdep 



At least POD HD500 uses message-based communication, both sides can
send messages. Add poll callback so application can wait for device
messages without using busy loop.

Signed-off-by: default avatarVasily Khoruzhick <anarsoul@gmail.com>
Link: https://lore.kernel.org/r/20200502193120.79115-3-anarsoul@gmail.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 5c2d0de5

sound/usb/line6/driver.c

+16 −0
Original line number Diff line number Diff line
@@ -630,11 +630,27 @@ line6_hwdep_write(struct snd_hwdep *hwdep, const char __user *data, long count, 
	return rv;

}



static __poll_t

line6_hwdep_poll(struct snd_hwdep *hwdep, struct file *file, poll_table *wait)

{

	__poll_t rv;

	struct usb_line6 *line6 = hwdep->private_data;



	poll_wait(file, &line6->messages.wait_queue, wait);



	mutex_lock(&line6->messages.read_lock);

	rv = kfifo_len(&line6->messages.fifo) == 0 ? 0 : EPOLLIN | EPOLLRDNORM;

	mutex_unlock(&line6->messages.read_lock);



	return rv;

}



static const struct snd_hwdep_ops hwdep_ops = {

	.open    = line6_hwdep_open,

	.release = line6_hwdep_release,

	.read    = line6_hwdep_read,

	.write   = line6_hwdep_write,

	.poll    = line6_hwdep_poll,

};



/* Insert into circular buffer */