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Message-Id: <1474660869-15532-2-git-send-email-zach.brown@ni.com>
Date: Fri, 23 Sep 2016 15:01:08 -0500
From: Zach Brown <zach.brown@...com>
To: ulf.hansson@...aro.org
Cc: adrian.hunter@...el.com, robh+dt@...nel.org, mark.rutland@....com,
linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, zach.brown@...com
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 <zach.brown@...com>
---
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"
--
2.7.4
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