diff options
| author | Daniel Drake <dsd@laptop.org> | 2012-11-25 22:02:54 +0400 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2012-12-06 22:55:05 +0400 |
| commit | 8ed765aac31b473e1881986d9fe2b6386f49f933 (patch) | |
| tree | 98c4a32d712ab6cab9e0b6258e19c3ade6b57f48 /Documentation | |
| parent | 6a66180a252f5856fc25de69c6313831f343f50f (diff) | |
| download | linux-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.txt | 2 |
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 |