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authorClemens Ladisch <clemens@ladisch.de>2008-02-25 10:59:52 +0100
committerTakashi Iwai <tiwai@suse.de>2008-04-24 12:00:15 +0200
commitea6b5828cdbbedaf26b12ae64befbec18084ea3c (patch)
tree5a02e041c96c4ec34c574c90b8b094935c03dfb4
parent47ba97f8fa01bb5b48e73b4b1271fbf1436a2d4b (diff)
[ALSA] mpu401: reduce tx loop timeout
Reduce the number of times to check for a non-empty Tx FIFO from 100 to 2 because there is no MPU-401 implementation that needs more than one or two reads to determine the actual FIFO status. Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
-rw-r--r--sound/drivers/mpu401/mpu401_uart.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/sound/drivers/mpu401/mpu401_uart.c b/sound/drivers/mpu401/mpu401_uart.c
index 5993864acbd3..dd6ec4266732 100644
--- a/sound/drivers/mpu401/mpu401_uart.c
+++ b/sound/drivers/mpu401/mpu401_uart.c
@@ -425,16 +425,17 @@ static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
{
unsigned char byte;
- int max = 256, timeout;
+ int max = 256;
do {
if (snd_rawmidi_transmit_peek(mpu->substream_output,
&byte, 1) == 1) {
- for (timeout = 100; timeout > 0; timeout--) {
- if (snd_mpu401_output_ready(mpu))
- break;
- }
- if (timeout == 0)
+ /*
+ * Try twice because there is hardware that insists on
+ * setting the output busy bit after each write.
+ */
+ if (!snd_mpu401_output_ready(mpu) &&
+ !snd_mpu401_output_ready(mpu))
break; /* Tx FIFO full - try again later */
mpu->write(mpu, byte, MPU401D(mpu));
snd_rawmidi_transmit_ack(mpu->substream_output, 1);