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Add calibration test to determine extent of AC97 overclocking (if any).

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This commit is contained in:
Orion Hodson 2001-12-18 03:29:31 +00:00
parent 99364715f7
commit 0225c5ac86
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=88108
1 changed files with 50 additions and 0 deletions
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50
sys/dev/sound/pci/ich.c
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@ -422,6 +422,55 @@ ich_initsys(struct sc_info* sc)
return 0;
}
/* -------------------------------------------------------------------- */
/* Calibrate card (some boards are overclocked and need scaling) */
static
unsigned int ich_calibrate(struct sc_info *sc)
{
/* Grab audio from input for fixed interval and compare how
* much we actually get with what we expect. Interval needs
* to be sufficiently short that no interrupts are
* generated. */
struct sc_chinfo *ch = &sc->ch[1];
u_int16_t target_picb, actual_picb;
u_int32_t wait_us;
int32_t actual_48k_rate;
KASSERT(ch->regbase == ICH_REG_PI_BASE, ("wrong direction"));
ichchan_setspeed(0, ch, 48000);
ichchan_setblocksize(0, ch, ICH_DEFAULT_BUFSZ);
target_picb = ch->dtbl[0].length / 2; /* half interrupt interval */
wait_us = target_picb * 1000 / (2 * 48); /* (2 == stereo -> mono) */
if (bootverbose)
device_printf(sc->dev, "Calibration interval %d us\n",
wait_us);
ichchan_trigger(0, ch, PCMTRIG_START);
DELAY(wait_us);
actual_picb = ich_rd(sc, ch->regbase + ICH_REG_X_PICB, 2);
ichchan_trigger(0, ch, PCMTRIG_ABORT);
actual_48k_rate = 48000 * (2 * target_picb - actual_picb) /
(target_picb);
if (bootverbose)
device_printf(sc->dev,
"Tgt PICB %d, Act PICB %d, 48k rate %d\n",
target_picb, actual_picb, actual_48k_rate);
if ((actual_48k_rate - 48000) > 500 ||
(actual_48k_rate - 48000) < -500) {
sc->ac97rate = actual_48k_rate;
} else {
sc->ac97rate = 48000;
}
return sc->ac97rate;
}
/* -------------------------------------------------------------------- */
/* Probe and attach the card */
@ -573,6 +622,7 @@ ich_pci_attach(device_t dev)
pcm_setstatus(dev, status);
ich_initsys(sc);
ich_calibrate(sc);
return 0;