ALSA: pcm - Fix delta calculation at boundary overlap

When the hw_ptr_interrupt reaches the boundary, it must check whether
the hw_base was already lapped and corret the delta value appropriately.

Also, rebasing the hw_ptr needs a correction because buffer_size isn't
always aligned to period_size.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 92ed6d819225..063c675177a9 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -221,8 +221,11 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
         new_hw_ptr = hw_base + pos;
         hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;
         delta = new_hw_ptr - hw_ptr_interrupt;
-        if (hw_ptr_interrupt == runtime->boundary)
-                hw_ptr_interrupt = 0;
+        if (hw_ptr_interrupt >= runtime->boundary) {
+                hw_ptr_interrupt %= runtime->boundary;
+                if (!hw_base) /* hw_base was already lapped; recalc delta */
+                        delta = new_hw_ptr - hw_ptr_interrupt;
+        }
         if (delta < 0) {
                 delta += runtime->buffer_size;
                 if (delta < 0) {
@@ -233,6 +236,8 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
                                      (long)hw_ptr_interrupt);
                         /* 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;
                 } else {
                         hw_base += runtime->buffer_size;