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ALSA: rawmidi: A lightweight function to discard pending bytes 

For discarding the pending bytes on rawmidi, we process with a loop of
snd_rawmidi_transmit() which is just a waste of CPU power.
Implement a lightweight API function to discard the pending bytes and
the proceed the ring buffer instantly, and use it instead of open
codes.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2018-09-13 08:20:43 +02:00
parent cd3b7116b5
commit 6aea5702e2
4 changed files with 25 additions and 5 deletions
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1
include/sound/rawmidi.h
View File

@ -171,6 +171,7 @@ int __snd_rawmidi_transmit_peek(struct snd_rawmidi_substream *substream,
unsigned char *buffer, int count);
int __snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream,
int count);
int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream);
/* main midi functions */

22
sound/core/rawmidi.c
View File

@ -1236,6 +1236,28 @@ int snd_rawmidi_transmit(struct snd_rawmidi_substream *substream,
}
EXPORT_SYMBOL(snd_rawmidi_transmit);
/**
* snd_rawmidi_proceed - Discard the all pending bytes and proceed
* @substream: rawmidi substream
*
* Return: the number of discarded bytes
*/
int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream)
{
struct snd_rawmidi_runtime *runtime = substream->runtime;
unsigned long flags;
int count = 0;
spin_lock_irqsave(&runtime->lock, flags);
if (runtime->avail < runtime->buffer_size) {
count = runtime->buffer_size - runtime->avail;
__snd_rawmidi_transmit_ack(substream, count);
}
spin_unlock_irqrestore(&runtime->lock, flags);
return count;
}
EXPORT_SYMBOL(snd_rawmidi_proceed);
static long snd_rawmidi_kernel_write1(struct snd_rawmidi_substream *substream,
const unsigned char __user *userbuf,
const unsigned char *kernelbuf,

4
sound/core/seq/seq_virmidi.c
View File

@ -149,9 +149,7 @@ static void snd_vmidi_output_work(struct work_struct *work)
/* discard the outputs in dispatch mode unless subscribed */
if (vmidi->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH &&
!(vmidi->rdev->flags & SNDRV_VIRMIDI_SUBSCRIBE)) {
char buf[32];
while (snd_rawmidi_transmit(substream, buf, sizeof(buf)) > 0)
; /* ignored */
snd_rawmidi_proceed(substream);
return;
}

3
sound/usb/midi.c
View File

@ -1175,8 +1175,7 @@ static void snd_usbmidi_output_trigger(struct snd_rawmidi_substream *substream,
if (port->ep->umidi->disconnected) {
/* gobble up remaining bytes to prevent wait in
* snd_rawmidi_drain_output */
while (!snd_rawmidi_transmit_empty(substream))
snd_rawmidi_transmit_ack(substream, 1);
snd_rawmidi_proceed(substream);
return;
}
tasklet_schedule(&port->ep->tasklet);