Hi! > >> When the FIFO is set to 128, it means that after the initial FIFO fill we will > >> have DMA request coming from McBSP to sDMA with a rate of: > >> > >> (1000/sampling_rate) * (FIFO-threshold / channels) = DMA_req_distance_in_ms > >> > >> So in case of 44.1KHz, stereo with 128 FIFO threshold DMA request will come at > >> every 1.45ms. If I'm not mistaken. The whole FIFO (1280) holds 14.51ms of > >> audio in this case. > >> > >> I don't see this correlate with the 30ms at all. > > > > It seems we easily have a situation where DMA is done buffering to McBSP, > > and PMIC is playing audio, and we hit idle. At that point there are no immediate > > timers pending and cpuidle determines we can try to hit a deeper idle mode. As > > there are no hardware blockers with DMA off and McBSP not blocking, the hardware > > hits off mode. This cuts power to McBSP. > > > > Ideally we'd configure McBSP activity to block deeper idle states in the > > hardware but I don't think we have such a configuration available. > > I wonder why we have not seen this before? I can not recall anything like this > with n900 (Jarkko might know that better) neither with n9/n950. On the n9/n950 > I have even put the OMAP3 to OFF during audio playback with the I was seeing something like that with 4.x kernel on Nokia N900. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
