[PATCH 1/2] fix-force-sdcard-clk-off-when-idle.patch

Werner Almesberger werner at openmoko.org
Sun Jul 20 16:08:23 CEST 2008

Andy Green wrote:
> I tested it briefly and was able to SD Boot normally on Sandisk 512M.
> Wider testing is appreciated.

Hmm, did you also check if the clock is really turned off ?

I just booted the kernel from the July 20 build, had a look at SD_CLK,
and it's there in all its vicious glory.

I killed off all processes but udevd, dropbear, getty, and the kernel
threads. The modules loaded are sound, OHCI, and BT. An SD card is
present but not mounted. The last attempts to access it failed with:

mmcblk0: error -110 sending read/write command
end_request: I/O error, dev mmcblk0, sector 0
Buffer I/O error on device mmcblk0, logical block 0

(Which is expected behaviour for this machine, since its SD/MMC is
known to be broken.)

So the idea that turning off the clock helps may still be correct,
(which I'd really appreciate, since nothing else sounds particularly
convincing ;-), the patch just doesn't do that, or at least not all
the time.

- Werner

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