2009/6/11 Daniel Ribeiro <drwyrm@xxxxxxxxx>:> Hi Eric,>> Em Ter, 2009-06-09 às 17:39 +0800, Eric Miao escreveu:>> frame_width = sample_width * channel ( = LRCLK for I2S )>>>> is no longer (and ever) correct.>>>> E.g. the frame width could be 64fs, meaning a whole frame is>> consisting>> of 64 bitclks - that's saying, sample width from 1 - 64 are possible,>> For typical 16-bit sample width I2S format, the envelope for each>> sample>> is 32 bitclks, and offseting by 1 bitclk starts the 16-bit sample.>> I'm working on supporting I2S right now, and I found some issues with> this enveloping thing.>> First, it doesn't work on pxa2xx. DMYSTOP on pxa2xx is only 0-3.
Well, there is a dedicated I2S controller on pxa{25x,27x}, so I'd expectif it's required for DMYSTOP > 3, the HW engineer would just resort tothe I2S controller.
>> Second, is enveloping needed at all? The patch you sent supports 32bits> frames for 2*16bits samples or 64bits frames for 2*32bits samples using> FSRT.>
There are some codecs requiring this.
> We already use FSRT for DSP_A, and if this works on littleton I2S we> should just stick with FSRT (and frame_width = sample_width * channels)> to keep the code simple.>
I hope so, but the assumption of frame_width == sample_width * 2 shouldhold true first.
>> And the TDM mode is actually special for PXA-SSP to emulate the I2S>> protocol, it's no way generic TDM in a common sense. So talking about>> set_tdm_slots(), I'd really like to hide into the format setting code>> of I2S/Left_J to avoid further confusion.>> TDM is needed for frames larger than 32 bits on any dai format. Its not> something specific to I2S.>
Well, emulating I2S with SSP has to use TDM mode so that a singleframe can include two samples._______________________________________________Alsa-devel mailing listAlsa-devel@xxxxxxxxxxxxxxxxxxxx://mailman.alsa-project.org/mailman/listinfo/alsa-devel
