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ALSA: rawmidi: A lightweight function to discard pending bytes

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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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22
sound/core/rawmidi.c
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@@ -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,