On Wed, Oct 5, 2016 at 1:33 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > On 23 September 2016 at 22:01, Zach Brown <zach.brown@xxxxxx> wrote: >> 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@xxxxxx> >> --- >> 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. If a controller has a capability register and it lies (perhaps the board has limitations that the SoC does not), then you may need to disable a feature. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
