Em Seg, 2009-06-08 às 17:53 +0100, Mark Brown escreveu: > > 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. I don't see why. If we provide an API to setup the frame size this is all magician needs. If we assume that the standard is frame_size = sample_size * channels, then there is no need for a frame size API at all. But then magician case will not be supported correctly. > 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. But for pxa-ssp this is not the current behaviour. Currently, the code uses frame_size = sample_size unless the machine driver explicitly calls set_tdm_slots. I believe that the correct behaviour would be frame_size = channels * sample size. Regarding tdm_slot(1, 1), it does not disable network mode, it setups DMA to 16bits regardless of 2 channels. > > 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? If we want to support magician, then set_frame_size(16) would also setup DMA for 16bits even for stereo audio. > > 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. I can cook a patch.. All I need to know is: Does it needs to support magician non-standard format? Or this will be handled by userspace? I think we can support magician case too, we just need to provide the set_frame_size api that was initially proposed. :) -- Daniel Ribeiro
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