Add a brief description about the newly added behavior of the PCM ack callback with -EPIPE error.
Signed-off-by: Takashi Iwai tiwai@suse.de --- Documentation/sound/kernel-api/writing-an-alsa-driver.rst | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst index 5c9523b7d55c..6b8f3495407f 100644 --- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst +++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst @@ -2137,6 +2137,10 @@ This callback is also not mandatory. This callback is called when the emu10k1-fx and cs46xx need to track the current ``appl_ptr`` for the internal buffer, and this callback is useful only for such a purpose.
+The callback function may return 0 or a negative error. When the +return value is ``-EPIPE``, PCM core treats as a buffer XRUN happens, +and changes the state to ``SNDRV_PCM_STATE_XRUN`` automatically. + This callback is atomic as default.
page callback