From: Clemens Ladisch Date: Mon, 25 Feb 2008 09:59:52 +0000 (+0100) Subject: [ALSA] mpu401: reduce tx loop timeout X-Git-Tag: Ubuntu-goldfish-3.4.0-4.27~19025^2~189 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=ea6b5828cdbbedaf26b12ae64befbec18084ea3c;p=mirror_ubuntu-zesty-kernel.git [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 --- 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);