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no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: <> List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Add a brief description about the newly added behavior of the PCM ack callback with -EPIPE error. Signed-off-by: Takashi Iwai --- 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