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[ALSA] intel8x0: add one retry to the ac97_clock measurement routine

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It seems that on some hardware platforms, the first measurement is wrong.
This patch adds second measurement to this case.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2009-04-15 10:16:24 +02:00
parent 29dab4fd31
commit 2ec775e705
1 changed files with 11 additions and 4 deletions
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15
sound/pci/intel8x0.c
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@ -2676,12 +2676,13 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
struct ichdev *ichdev;
unsigned long port;
unsigned long pos, pos1, t;
int civ, timeout = 1000;
int civ, timeout = 1000, attempt = 1;
struct timespec start_time, stop_time;
if (chip->ac97_bus->clock != 48000)
return; /* specified in module option */
__again:
subs = chip->pcm[0]->streams[0].substream;
if (! subs || subs->dma_buffer.bytes < INTEL8X0_TESTBUF_SIZE) {
snd_printk(KERN_WARNING "no playback buffer allocated - aborting measure ac97 clock\n");
@ -2749,6 +2750,11 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
if (pos == 0) {
snd_printk(KERN_ERR "intel8x0: measure - unreliable DMA position..\n");
__retry:
if (attempt < 2) {
attempt++;
goto __again;
}
return;
}
@ -2759,14 +2765,15 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
printk(KERN_INFO "%s: measured %lu usecs (%lu samples)\n", __func__, t, pos);
if (t == 0) {
snd_printk(KERN_ERR "intel8x0: ?? calculation error..\n");
return;
goto __retry;
}
pos *= 1000;
pos = (pos / t) * 1000 + ((pos % t) * 1000) / t;
if (pos < 40000 || pos >= 60000)
if (pos < 40000 || pos >= 60000) {
/* abnormal value. hw problem? */
printk(KERN_INFO "intel8x0: measured clock %ld rejected\n", pos);
else if (pos > 40500 && pos < 41500)
goto __retry;
} else if (pos > 40500 && pos < 41500)
/* first exception - 41000Hz reference clock */
chip->ac97_bus->clock = 41000;
else if (pos > 43600 && pos < 44600)