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Suggested-by: Werner Almesberger <werner@openmoko.org>
This patch allows users to control two additional settings
in Glamo MCI driver from kernel commandline or module
parameters.
First is Glamo drive strength on SD IOs including CLK.
This ranges from 0 (weakest) to 3 (strongest).
echo 0 > /sys/module/glamo_mci/parameters/sd_drive
(Changes to this take effect on next SD Card transaction)
or, from kernel commandline
glamo_mci.sd_drive=0
On tests here with 0 strength, communication to SD card
(shipped 512MB Sandisk) seemed fine, and a dd of 10MB
urandom had the same md5 when written to cache as after
a reboot. I set the default to 2.
Second is whether we allow SD_CLK when the SD interface
is idle.
# stop the clock when we are idle (default)
echo 0 > /sys/module/glamo_mci/parameters/sd_idleclk
# run the SD clock all the time
echo 1 > /sys/module/glamo_mci/parameters/sd_idleclk
(changes take effect on next SD Card transaction)
From kernel commandline, eg:
glamo_mci.sd_idleclk=1
Normally you don't want to run the SD Clock all the time.
Signed-off-by: Andy Green <andy@openmoko.com>
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Reported-by: Ville-Pekka Vainio <vpivaini@cs.helsinki.fi>
The reporter noticed SD Card clock is running again after resume. After
looking at the code I saw I missed two tricks, this will force it off
after resume and will do better generally depending on what the last SD Card
packet was.
Since bulk read packet is normally last action (which set the clock off even
without this) the old patch worked for normal cases. But after resume, the last
packet on the wire was not a bulk transfer and we didn't take care about the
clock then.
Signed-off-by: Andy Green <andy@openmoko.com>
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This patch allows you to control the maximum clock rate that will
be selected for SD Card access, from the kernel commandline using
glamo_mci.sd_max_clk=10000000
and also from
echo 10000000 > /sys/module/glamo_mci/parameters/sd_max_clk
although you have to suspend and resume to make the limit operational
on the actual SD_CLK line.
Clocks that are possible are divided down from ~50MHz, so 25000000,
16666666, 12500000, 10000000, etc. With Freerunner A5 revision that
has 100R series resistors in SD Card signals, I didn't get reliable
operation above 16MHz. With A6 revision the series resistors went
down to 75R, maybe it can work at 25MHz.
Reducing the clock rate is something to try if you find that your
SD Card is not communicating properly with the default speed.
Signed-off-by: Andy Green <andy@openmoko.com>
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Existing Glamo bit for stopping SD Card Clock when there is no
transfer taking place does not work. This patch adds stuff around
the transfer code to force the SD clock up when something is going on
and down when it is idle. This'll save a little power and noise ;-)
I tested it briefly and was able to SD Boot normally on Sandisk 512M.
Wider testing is appreciated.
Signed-off-by: Andy Green <andy@openmoko.com>
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Glamo MCI has a resume order dependncy on pcf50633, it has to be able to
power the SD slot via it.
Signed-off-by: Andy Green <andy@openmoko.com>
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Signed-Off-By: Holger Freyther <zecke@openmoko.org>
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We need to be able to use the config option CONFIG_MMC_UNSAFE_RESUME that allows the rootfs
to live on SD. But when we use this, it tries to send a reset command to the SD card during
suspend -- and unfortunately many things like Power have suspended by then.
This patch again rejects IO on the MMC device during suspend of the MMC device, and it
gives the result the rootfs on SD card works okay.
Signed-off-by: Andy Green <andy@openmoko.com>
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