[alsa-devel] MPC5200 I2S driver for ASoC

lokowich lokowich at acdstar.com
Wed Aug 1 21:16:23 CEST 2007

Timur Tabi wrote:
> lokowich wrote:
>> I'm integrating a ALSA driver for an MPC5200 into the ASoC layer, 
>> similar to my successful effort for a PXA255 board.  
> Can you provide your code?  I'm working on ASoC support for another MPC SOC, so we need to 
> synchronize our development.

    Yes, I presume you mean using git into the ALSA branch.  I need to
    get more familiar with git, and follow the appropriate coding
    conventions before it's ready.  Any guidance will be appreciated.

> I'm modeling the 
> DMA and ALSA interfaces per ac97mgt driver found in the Lite5200B BSP, 
> rather than the BestComm API example in the 2.4 kernel.  The 
> speaker-test with 400Hz sine wave is working, but has a slight audible 
> jitter.  A wav file output using aplay produces white noise.  
> What kind of audio samples are you trying to play?  Since the MPC5200 is typically 
> big-endian, you probably can only play S16_BE samples instead of S16_LE samples.

    Yes!  I had enabled the S16_BE format in my codec/i2s/pcm driver,
    but naively thought ALSA would handle the rest.  Converted my test
    file to S16_BE and it sounds much closer to the original.  Thanks!
    Found the "jitter" is due to a FIFO overflow.  I'm using same alarm
    (0x120) and granularity (4) common to 2.4 I2S and ac97 drivers.  Is
    there a more appropriate setting for 16-bit, 2-channel, 44.1kHz audio?

    Also, can we chat about SDRAM problems on 5200B outside of this forum?

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