On Thu, 12 Feb 2004, Gupta, Kshitij wrote:
> hi,
>
> yeah that's true I2S has not much to with the driver. So there is
> one more component on the chip called McBSP(Multichannel Buffered serial
> port) which will actually communicate to the codec chip over I2S protocol.
> And the DMA can read data from the McBSP recieve and transmit buffers. But
> still the driver has to do the McBSP configuration.
> The kind of functionality the driver should provide is
>
> - Codec Control
> xxx_codec_write
> xxx_codec_read
> for reading and writing to the codec control bits. This will be done via
> SPI interface.
So, look to alsa-kernel/i2c directory for examples, how to write a library
for such codecs. We prefer to create a library than controlling codecs in
the toplevel driver, because we can reuse code later.
> - Dma Control functions
> start_dma
> queue_dma
> stop_dma ...
Exactly. In this case, you may look to any ISA/PCI drivers what the
callbacks from midlevel do.
If you have a specific question, we are here ;-)
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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