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Use correct sequence for resetting CORB read pointer

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* Spec requires software to wait for hardware to acknowledge the
  reset by waiting for the bit to become set and then manually
  unset it and again wait for it to become unset.
  (cf. HDA spec 1.0a ch. 3.3.21)

* Also, do read-modify-write to protect preserved bits
This commit is contained in:
Julian Harnath 2014-09-01 21:47:04 +02:00
parent 78b950bd2d
commit 2d498c889c
1 changed files with 32 additions and 5 deletions
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37
src/add-ons/kernel/drivers/audio/hda/hda_controller.cpp
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@ -495,11 +495,38 @@ init_corb_rirb_pos(hda_controller* controller)
((uint8*)controller->corb + posOffset);
controller->Write16(HDAC_CORB_WRITE_POS, 0);
// Reset CORB read pointer
controller->Write16(HDAC_CORB_READ_POS, CORB_READ_POS_RESET);
// Reading CORB_READ_POS_RESET as zero fails on some chips.
// We reset the bit here.
controller->Write16(HDAC_CORB_READ_POS, 0);
// Reset CORB read pointer. Preseve bits marked as RsvdP.
// After setting the reset bit, we must wait for the hardware
// to acknowledge it, then manually unset it and wait for that
// to be acknowledged as well.
uint16 corbReadPointer = controller->Read16(HDAC_CORB_READ_POS);
corbReadPointer |= CORB_READ_POS_RESET;
controller->Write16(HDAC_CORB_READ_POS, corbReadPointer);
for (int timeout = 0; timeout < 10; timeout++) {
snooze(100);
corbReadPointer = controller->Read16(HDAC_CORB_READ_POS);
if ((corbReadPointer & CORB_READ_POS_RESET) != 0)
break;
}
if ((corbReadPointer & CORB_READ_POS_RESET) == 0) {
dprintf("hda: CORB read pointer reset failed\n");
return B_BUSY;
}
corbReadPointer &= ~CORB_READ_POS_RESET;
controller->Write16(HDAC_CORB_READ_POS, corbReadPointer);
for (int timeout = 0; timeout < 10; timeout++) {
snooze(100);
corbReadPointer = controller->Read16(HDAC_CORB_READ_POS);
if ((corbReadPointer & CORB_READ_POS_RESET) == 0)
break;
}
if ((corbReadPointer & CORB_READ_POS_RESET) != 0) {
dprintf("hda: CORB read pointer reset failed\n");
return B_BUSY;
}
// Reset RIRB write pointer
controller->Write16(HDAC_RIRB_WRITE_POS, RIRB_WRITE_POS_RESET);