Jyri Sarha wrote: > On 09/21/15 12:37, Russell King - ARM Linux wrote: >> ALSA documentation (which may be out of date) says that the hw_params >> callback can be called multiple times during stream setup. Do we want >> to be repeatedly programming the HDMI infoframe with different settings, >> potentially confusing the attached device, or would it be better to do >> it slightly later (in the prepare callback) after the parameters have >> been fully negotiated? > > If it is possible that hw_params() can be called multiple times, at > least it does not happen very often. I wonder if it would ever happen > again after a successful hw_params() call. It is certainly allowed, and it happens regularly when using OSS emulation. AFAIK PulseAudio does something similar when enumerating devices. > But there is no downside in using prepare callback. The prepare callback also can be called multiple times. This certainly happens when the stream is stopped/restarted multiple times. If something does not need to be done again when a stream is restarted, then it should be done in the hw_params callback. Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
