9629581258
The indirect-PCM helper codes have an implicit assumption that the appl_ptr always increases. But the PCM core may deal with the decrement of appl_ptr via rewind ioctls, and it may screw up the buffer pointer management. This patch adds the negative appl_ptr diff in transfer functions and let returning an error instead of always accepting the appl_ptr updates. The callers are usually PCM ack callbacks, and they pass the error to the upper layer accordingly. Signed-off-by: Takashi Iwai <tiwai@suse.de>