On Thu, Feb 9, 2012 at 3:09 AM, Philip Rakity [off-list ref] wrote:

quoted

Jeff,

I think the sdhci.c clock setting code was changed a while ago.   Maybe revert that mod and see what happens.

The card is a 24MHz which is rather slow so I would be surprised if that was it.
The other option is the force enable the High Speed bit in the  controller (used when speed is 25MHz or faster).  Will give the system more time (in theory) to work.

That's a good point to start looking. I poked around and by setting
host->ios.clock to 10000000 instead of 25000000, read from a 16GB card
is no longer giving any error.

I still don't dare to do any write. Already burn one 16GB SD and not
ready to trash another. I asked earlier but haven't got any reply as
to how to recover an SD that says "No medium found". Any chance of
recovering it?

Here's what I did. If set too low (1000000) or too high (25000000),
random errors appeared.

--- linux/drivers/mmc/core/core.c.org   2012-02-10 23:57:49.000000000 +0800
+++ linux/drivers/mmc/core/core.c       2012-02-10 23:53:59.000000000 +0800

@@ -881,7 +881,7 @@
       if (hz > host->f_max)
               hz = host->f_max;

-       host->ios.clock = hz;
+       host->ios.clock = 10000000;
       mmc_set_ios(host);

}