On Mon, Jun 08, 2009 at 01:03:20PM -0300, Daniel Ribeiro wrote: > Em Seg, 2009-06-08 às 13:40 +0100, Mark Brown escreveu: > > I'm inclined to go with sample here since it seems harder for the > > machine drivers to get wrong but I've not really thought it through yet? > But sample wouldn't cover all cases. eg, magician and ezx uses the same > sample size, but magician needs 16bit frames and ezx 32bits frames. See my reply to Philip - even with frame size his case is going to be very hard to cover in a standard fashion since it's not clear what to do when your frame clock is run too fast relative to your bit clock. On the receive side a lot of devices are just going to discard incomplete stereo frames. > Just to confirm that I'm understanding the terminology here.. > Sample size is SNDRV_PCM_FORMAT_*, and frame size is the actual distance > in clocks between each SSPFRM assertion. Is this correct? That's pretty much my understanding - sample size is the number of bits clocked per mono sample on the wire and frame size is the number of bits clocked per cycle of the frame clock. > > OTOH I don't really see much difference between the two cases - it's > > just an extra couple of parameters on the end of the call. That said, > I agree with pHilipp, I don't need to set network mode for normal > operation, but i want to be able to use real network mode. Network mode is just a detail of the implementation of the PXA here - it should not be visible outside the pxa-ssp driver. Or to put it another way setting a tdm_slot of 1, 1 ought to result in the same behaviour as disabling TDM as far as the user is concerned. > Using set_tdm_slot to setup this also seems awkward, because the dma > configuration to use is also affected by the frame size. I'd not expect it to be? > And finally, set_tdm_mode doesn't cover all use cases, I may want to > receive on a timeslot and keep the TX line high impedance, or I may want > to use a different timeslot for TX... Yes, set_tdm_mode() needs separate RX and TX configuration regardless - if we added the framing configuration in there we should definitely make that change at that point. > My suggestion here is to make a clear distinction between normal mode > and network mode. We should not abuse SSCR0_MOD when we don't need it. > We should not require the machine driver to call set_tdm_slot when it > doesn't need to. And for frame sizes that really need SSCR0_MOD to be > set we should issue a warning telling that network mode was > "automatically" enabled. I'd like to see all these details handled within the driver - knowing if and when network mode are to be set up is the sort of thing that users ought to be able to rely on the driver for. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
