[alsa-devel] MPC5200 I2S driver for ASoC
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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