Add bindings documentation for pad pull up and pull down offset values to be
programmed before executing automatic pad drive strength calibration.
Signed-off-by: Aapo Vienamo <avienamo@xxxxxxxxxx>
Acked-by: Thierry Reding <treding@xxxxxxxxxx>
---
.../bindings/mmc/nvidia,tegra20-sdhci.txt | 35 +++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt b/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
index 90c214dbfb16..9713e052f736 100644
--- a/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
+++ b/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
@@ -45,6 +45,37 @@ Optional properties for Tegra210 and Tegra186:
for controllers supporting multiple voltage levels. The order of names
should correspond to the pin configuration states in pinctrl-0 and
pinctrl-1.
+- nvidia,only-1-8-v : The presence of this property indicates that the
+ controller operates at a 1.8 V fixed I/O voltage.
+- nvidia,pad-autocal-pull-up-offset-3v3,
+ nvidia,pad-autocal-pull-down-offset-3v3 : Specify drive strength
+ calibration offsets for 3.3 V signaling modes.
+- nvidia,pad-autocal-pull-up-offset-1v8,
+ nvidia,pad-autocal-pull-down-offset-1v8 : Specify drive strength
+ calibration offsets for 1.8 V signaling modes.
+- nvidia,pad-autocal-pull-up-offset-3v3-timeout,
+ nvidia,pad-autocal-pull-down-offset-3v3-timeout : Specify drive
+ strength used as a fallback in case the automatic calibration times
+ out on a 3.3 V signaling mode.
+- nvidia,pad-autocal-pull-up-offset-1v8-timeout,
+ nvidia,pad-autocal-pull-down-offset-1v8-timeout : Specify drive
+ strength used as a fallback in case the automatic calibration times
+ out on a 1.8 V signaling mode.
+- nvidia,pad-autocal-pull-up-offset-sdr104,
+ nvidia,pad-autocal-pull-down-offset-sdr104 : Specify drive strength
+ calibration offsets for SDR104 mode.
+- nvidia,pad-autocal-pull-up-offset-hs400,
+ nvidia,pad-autocal-pull-down-offset-hs400 : Specify drive strength
+ calibration offsets for HS400 mode.
+
+ Notes on the pad calibration pull up and pulldown offset values:
+ - The property values are drive codes which are programmed into the
+ PD_OFFSET and PU_OFFSET sections of the
+ SDHCI_TEGRA_AUTO_CAL_CONFIG register.
+ - A higher value corresponds to higher drive strength. Please refer
+ to the reference manual of the SoC for correct values.
+ - The SDR104 and HS400 timing specific values are used in
+ corresponding modes if specified.
Example:
sdhci@700b0000 {
@@ -58,5 +89,9 @@ sdhci@700b0000 {
pinctrl-names = "sdmmc-3v3", "sdmmc-1v8";
pinctrl-0 = <&sdmmc1_3v3>;
pinctrl-1 = <&sdmmc1_1v8>;
+ nvidia,pad-autocal-pull-up-offset-3v3 = <0x00>;
+ nvidia,pad-autocal-pull-down-offset-3v3 = <0x7d>;
+ nvidia,pad-autocal-pull-up-offset-1v8 = <0x7b>;
+ nvidia,pad-autocal-pull-down-offset-1v8 = <0x7b>;
status = "disabled";
};
--
2.18.0
