I am having problems with a sound driver for a custom ARM PXA27x embedded device.

I recently upgraded a custom 2.6.17 kernel to 2.6.30 and all devices work correctly. The upgrade was performed 'blind' - i.e:
1 - I am new to kernel development and the 2.6.17
2 - I was using was supplied by a third party a
3 - The 2.6.17 kernel differed greatly from the official 2.6.17 base kernel.
4 - This kernel includes custom drivers for sound, using SPI.

I have recently attempted to upgrade to the newer 2.6.31 kernel, unfortunately the sound driver is not working correctly, even though the driver source code is unchanged between the 2.6.30 and 2.6.31.

No errors are reported during bootup. If I attempt to play any sounds no errors are reported by the driver, even though no sound is actually played back. By adding debug information I have proved that the pcm driver is attempting to write data out of the SSP port (uising SPI).

Using an oscilloscope it appears that although the driver is attempting playback, each sound frame is not being clocked out correctly.

So far I have been unable to find any differences in the way that SPI is configured by the 2.6.30 and 2.6.31 drivers.

The PCM sound driver I am using has remained virtually unchanged from the original 2.6.17 kernel version. Has something fundamental changed in the way that SPI is configured that I need to consider for this driver?

Is there anything new that I need to consider for the 2.6.31 driver?

Any suggestions are greatly appreciated.

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