Pierre-Louis, On Jun 12 2017 21:09, Pierre-Louis Bossart wrote: >> If describing the detail design of your hardware, you might get more >> helps. >> >> * I intentionally ignore discussion about burstness of data >> transmission and accuracy of hwptr. > > You are probably reading too much into this. > The intent is to optimize DMA operations where the hardware now knows > both hw_ptr and appl_ptr. there is no use of the .ack() for copies into > intermediate buffers If this patch included enough explanation about the disadvantage of rewind operation on your driver and hardware in a point of optimization for DMA data transmission and power consumption, I would not have driven my imagination so hard for the reviewing. > and the code for rewind on capture is largely for > consistency - we've never seen anyone using rewind on capture on > DSP-based platforms. I'm not a prophet, and you too. It's not better to change interfaces with any forecast. Furthermore, once changing interfaces, it affects to all of applications. Please have enough care of it. # I can imagine a disadvantage of rewind operation for PCM capture # substream. When rewinding, available space on PCM buffer for data # transmission from hardware is reduced. Then, even if hardware already # done sampling, it can't transfer the PCM frames. There's a delay and # hardware needs extra buffering. Regards Takashi Sakamoto _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
