Re: [RFC 1/2] sdhci: Add device tree property sd-broken-highspeed
From: Ulf Hansson <hidden>
Date: 2016-10-05 18:40:56
Also in:
linux-mmc, lkml
On 23 September 2016 at 22:01, Zach Brown [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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.
Regarding a broken card, that is managed via the card quirks and not in DT. If this is about a controller limitation, we already have the option to describe what it supports, so we don't need an option to tell what it *not* supports. For example "cap-sd-highspeed" tells whether the controller supports SD high-speed, please use that instead.
*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
Kind regards Uffe