Commit 6aea5702 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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: default avatarTakashi Iwai <tiwai@suse.de>
parent cd3b7116

include/sound/rawmidi.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

sound/core/rawmidi.c

+22 −0
Original line number Diff line number Diff line
@@ -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,

sound/core/seq/seq_virmidi.c

+1 −3
Original line number Diff line number Diff line
@@ -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;

	}

sound/usb/midi.c

+1 −2
Original line number Diff line number Diff line
@@ -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);

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