Commit 79452f0a authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm - Fix regressions with VMware 



VMware tends to report PCM positions and period updates at utterly
wrong timing.  This screws up the recent PCM core code that tries
to correct the position based on the irq timing.

Now, when a backward irq position is detected, skip the update
instead of rebasing.  (This is almost the old behavior before
2.6.30.)

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 6847e154

sound/core/pcm_lib.c

+10 −1
Original line number Diff line number Diff line
@@ -244,6 +244,7 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream) 
			delta = new_hw_ptr - hw_ptr_interrupt;

	}

	if (delta < 0) {

		if (runtime->periods == 1)

			delta += runtime->buffer_size;

		if (delta < 0) {

			hw_ptr_error(substream,
@@ -251,11 +252,19 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream) 
				     "(stream=%i, pos=%ld, intr_ptr=%ld)\n",

				     substream->stream, (long)pos,

				     (long)hw_ptr_interrupt);

#if 1

			/* simply skipping the hwptr update seems more

			 * robust in some cases, e.g. on VMware with

			 * inaccurate timer source

			 */

			return 0; /* skip this update */

#else

			/* rebase to interrupt position */

			hw_base = new_hw_ptr = hw_ptr_interrupt;

			/* align hw_base to buffer_size */

			hw_base -= hw_base % runtime->buffer_size;

			delta = 0;

#endif

		} else {

			hw_base += runtime->buffer_size;

			if (hw_base >= runtime->boundary)

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