SDHC card affected by preemption model in 2.6.35

[Mathieu Poirier <mathieu.poirier@canonical.com>]

HW: Beagleboard rev. C2 and C4
Processor: OMAP3
Kernel: 2.6.35-rc2
Driver: mmci-omap-hs

I am faced with an SDHC card problem on a beagleboard.  Some cards
cannot be initialized on startup while others work perfectly.  I tracked
the issue down to one single kernel config: PREEMPT_VOLUNTARY.  

When going from PREEMPT_VOLUNTARY to PREEMPT_NONE the problem goes away.

When booting, a failing card (PREEMPT_VOLUNTARY) will output the
following: 
[ 2.283355] mmc0: error -110 whilst initialising SD card

I have also seen transfer errors such as this one: 
[ 105.343780] mmcblk0: error -110 transferring data, sector 798431, nr
26, card status 0xc00 

When working properly (PREEMPT_NONE), you get: 
[   27.026519] mmc0: new high speed SDHC card at address 0007
[   27.075775] mmcblk0: mmc0:0007 SD08G 7.49 GiB 

We seem to have a little timing problem - has anyone seen the same
issue ?  Can driver "mmci-omap-hs" actually work under
PREEMPT_VOLUNTARY ? 

Thanks, Mathieu.