From f708eb1d71dc8ffb184da9f0bc53461c6dc10653 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 15 Jun 2009 12:31:38 +0200 Subject: [PATCH] ALSA: intel8x0 - Fix PCM position craziness The PCM pointer callback sometimes returns invalid positions and this screws up the hw_ptr updater in PCM core. Especially since now the jiffies check is optional with xrun_debug, the invalid position is handled as is, and causes serious sound skips, etc. This patch simplifies the position-fix strategy in intel8x0 to be more robust: - just falls back to the last position if bogus position is detected - another sanity check for the backward move of the position due to a race of register update and the base-index update This patch is applicable also for 2.6.30. Tested-by: David Miller Cc: Signed-off-by: Takashi Iwai --- sound/pci/intel8x0.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c index 173bebf9f51d..8aa5687f392a 100644 --- a/sound/pci/intel8x0.c +++ b/sound/pci/intel8x0.c @@ -356,8 +356,6 @@ struct ichdev { unsigned int position; unsigned int pos_shift; unsigned int last_pos; - unsigned long last_pos_jiffies; - unsigned int jiffy_to_bytes; int frags; int lvi; int lvi_frag; @@ -844,7 +842,6 @@ static int snd_intel8x0_pcm_trigger(struct snd_pcm_substream *substream, int cmd case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: val = ICH_IOCE | ICH_STARTBM; ichdev->last_pos = ichdev->position; - ichdev->last_pos_jiffies = jiffies; break; case SNDRV_PCM_TRIGGER_SUSPEND: ichdev->suspended = 1; @@ -1048,7 +1045,6 @@ static int snd_intel8x0_pcm_prepare(struct snd_pcm_substream *substream) ichdev->pos_shift = (runtime->sample_bits > 16) ? 2 : 1; } snd_intel8x0_setup_periods(chip, ichdev); - ichdev->jiffy_to_bytes = (runtime->rate * 4 * ichdev->pos_shift) / HZ; return 0; } @@ -1073,19 +1069,23 @@ static snd_pcm_uframes_t snd_intel8x0_pcm_pointer(struct snd_pcm_substream *subs ptr1 == igetword(chip, ichdev->reg_offset + ichdev->roff_picb)) break; } while (timeout--); + ptr = ichdev->last_pos; if (ptr1 != 0) { ptr1 <<= ichdev->pos_shift; ptr = ichdev->fragsize1 - ptr1; ptr += position; - ichdev->last_pos = ptr; - ichdev->last_pos_jiffies = jiffies; - } else { - ptr1 = jiffies - ichdev->last_pos_jiffies; - if (ptr1) - ptr1 -= 1; - ptr = ichdev->last_pos + ptr1 * ichdev->jiffy_to_bytes; - ptr %= ichdev->size; + if (ptr < ichdev->last_pos) { + unsigned int pos_base, last_base; + pos_base = position / ichdev->fragsize1; + last_base = ichdev->last_pos / ichdev->fragsize1; + /* another sanity check; ptr1 can go back to full + * before the base position is updated + */ + if (pos_base == last_base) + ptr = ichdev->last_pos; + } } + ichdev->last_pos = ptr; spin_unlock(&chip->reg_lock); if (ptr >= ichdev->size) return 0; -- 2.20.1