[alsa-devel] Problem to init AD1938 on i.MX25

Sven Zeisberg sven.zeisberg at googlemail.com
Mon Aug 16 10:39:40 CEST 2010

  Thank you, Sascha, for helping!

You're probably right - there is actually no "i.MX25" path in the SPI 
Since I'm on a congress for the rest of the week, a colleague of mine 
will takeover and return with the results of the test you suggested.

*/Sven Chris Zeisberg
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Am 16.08.2010 09:30, schrieb Sascha Hauer:
> Hello Sven,
> On Mon, Aug 16, 2010 at 06:51:17AM +0200, Sven Zeisberg wrote:
>>    Hello,
>> we're working on an ALSA  driver for AD1938 for i.MX25 based system.
>> On the I²S the CODEC is Master. On the SPI, the MCU is Master.
>> SSI seems to work (when we set the CODEC as Master by Hardware).
>> We have problems to get the communication via SPI working. The CODEC
>> requires 24Bit words and we can set SPI according to this in the
>> board-file and verify this also with a logic analyzer. However, we can
>> send only one word to the CODEC! This first word is transferred
>> correctly, but all subsequent transfers show no activity on the SPI
>> lines. We do not get any error messages from the SPI drivers! All SPI
>> writes after the first word seem to be executed in software but show not
>> effect in hardware. All reads return 0xff.
> This is probaly more a problem in the SPI driver than alsa related. The
> i.MX SPI unit comes in many different variants and there may well be a
> bug in the i.MX25 path. As a test you could configure the SPI pads in
> gpio mode and use the bitbang gpio spi driver (drivers/spi/spi_gpio.c).
> When this works you can hunt down the bug in the SPI driver.
> Sascha

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