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Subject[RFC 1/2] sdhci: Add device tree property sd-broken-highspeed
Certain board configurations can make highspeed malfunction due to
timing issues. In these cases a way is needed to force the controller
and card into standard speed even if they otherwise appear to be capable
of highspeed.

The sd-broken-highspeed property will let the sdhci driver know that
highspeed will not work.

Signed-off-by: Zach Brown <>
Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 8a37782..59332ea 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -52,6 +52,8 @@ Optional properties:
- no-sdio: controller is limited to send sdio cmd during initialization
- no-sd: controller is limited to send sd cmd during initialization
- no-mmc: controller is limited to send mmc cmd during initialization
+- sd-broken-highspeed: Highspeed is broken, even if the controller and card
+ themselves claim they support highspeed.

*NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
polarity properties, we have to fix the meaning of the "normal" and "inverted"
 \ /
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