Re: [Bug 39822] SDHC cards no longer recognized on AT91 based board

[Douglas Gilbert <dgilbert@interlog.com>]

On 11-07-28 07:48 PM, Chris Ball wrote:
> Hi, thanks for the bug report.  Adding linux-mmc@ and some atmel driver
> folks to CC.
>
> On Thu, Jul 28 2011, bugzilla-daemon@bugzilla.kernel.org wrote:
>> Prior to 3.0.0 the FoxG20 board (Atmel AT91SAM9G20) could boot and use
>> both micro SD and SDHC card to contain its root file system. With the
>> advent of the 3.0.0 kernel the micro SDHC card is unable to mount the
>> root file system.
>>
>> Comparing the relevant part of dmesg for 2.6.38.6 (and it worked on
>> 2.6.39):
>> ...
>> Waiting for root device /dev/mmcblk0p2...
>> mmc0: host does not support reading read-only switch. assuming write-enable.
>> at91_mci at91_mci: Timeout waiting end of packet
>> mmc0: new SDHC card at address 1234
>> mmcblk0: mmc0:1234 SA04G 3.67 GiB
>>   mmcblk0: p1 p2 p3
>> ...
>>
>> to the same dmesg section for 3.0.0 :
>> ...
>> Waiting for root device /dev/mmcblk0p2...
>> mmc0: error -110 whilst initialising SD card
>> at91_mci at91_mci: Timeout waiting end of packet
>> mmc0: error -110 whilst initialising SD card
>> [no further progress]
>>
>> Non "HC" SD cards work as expected in 3.0.0
>
> If no-one on the CC list has any ideas, would you be interested in
> trying to bisect this change?
>
> Another possibility would be adding printks before all of the -ETIMEDOUT
> lines in core/* and host/at*, in order to see which one you're hitting
> (and therefore which operation is causing the initialization to fail).
> But a full bisection would be more conclusive.

Sorry, I keep away from git. But the smoking gun is
drivers/mmc/core/sd.c that underwent major changes
to support SDXC between 2.6.39 and 3.0.0 .

Luckily I can revert core/sd.c to the state it was in
in lk 2.6.38.6 and it compiles in 3.0.0 . With that kernel
my Fox G20 can read its root fs from a SDHC card.

BTW With lk 2.6.39 the Fox G20 booted okay from a SDHC
card but that kernel had other (UDP broadcast) problems.