From: Larry Martin <Larry@GlueLogix.com> - 2010-10-07 13:49:49
What is the accepted method for getting to the mmc_set_ios() method?
I want to lower the Verdex Pro MMC clock by passing in a nonstandard
clock rate. The pxamci driver refreshes the CLKRT register from the
stored value on each pxamci_start_cmd(), which chains from
mmc_start_request(). It looks like you have to compute your desired
clock rate by dividing the max clock by a power of two between 0 and 6.
You then pass that value in to mmc_set_ios(), using an mmc_ios
structure, and let pxamci_set_ios() reverse the computation. The end
result is a three bit number in CLKRT.
I have looked for a command line interface in /proc and /sys with no
success. I am currently looking at modprobe with parameters and
eventually a C program, but would be very grateful if someone would
share a command line access method.
From: Ash Charles <ashcharles@gm...> - 2010-10-07 17:13:11
On Thu, Oct 7, 2010 at 6:49 AM, Larry Martin <Larry@...> wrote:
> I have looked for a command line interface in /proc and /sys with no
> success. I am currently looking at modprobe with parameters and
> eventually a C program, but would be very grateful if someone would
> share a command line access method
Interesting question. You've clearly looked into the guts of the mmc
system on the PXA270 more than I have so I can't comment on your
finding. But for command line control of processor registers, I find
the 'pxaregs' program useful (see
http://www.mn-logistik.de/unsupported/pxa250/ & the source code for
more info) ---perhaps this gives you the ability to change MMC_CLKRT
etc. as appropriate?
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