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authorDaniel Drake <dsd@laptop.org>2012-11-25 22:02:54 +0400
committerChris Ball <cjb@laptop.org>2012-12-06 22:55:05 +0400
commit8ed765aac31b473e1881986d9fe2b6386f49f933 (patch)
tree98c4a32d712ab6cab9e0b6258e19c3ade6b57f48 /Documentation
parent6a66180a252f5856fc25de69c6313831f343f50f (diff)
downloadlinux-8ed765aac31b473e1881986d9fe2b6386f49f933.tar.xz
mmc: dt: add no-1-8-v device tree flag
The OLPC XO-1.75 laptop includes a SDHCI controller which is 1.8v capable, and it truthfully reports so in its capabilities. This alternate voltage is used for driving new "UHS-I" SD cards at their full speed. However, what the controller doesn't know is that the motherboard physically doesn't have a 1.8v supply available, so attempting to switch to the 1.8v level will result in a situation that cannot be recovered from without physically replugging the SD card. Add a device tree flag that can be used on systems like these, and hook it up to the equivalent SDHCI quirk. Signed-off-by: Daniel Drake <dsd@laptop.org> Reviewed-by: Philip Rakity <prakity@nvidia.com> Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/mmc/mmc.txt2
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index b96e510979bf..a591c6741d75 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -21,6 +21,8 @@ Optional properties:
- cd-inverted: when present, polarity on the cd gpio line is inverted
- wp-inverted: when present, polarity on the wp gpio line is inverted
- max-frequency: maximum operating clock frequency
+- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
+ this system, even if the controller claims it is.
Optional SDIO properties:
- keep-power-in-suspend: Preserves card power during a suspend/resume cycle