linux-kernel - Re: [PATCH 05/10] dt-bindings: Add Tegra SDHCI pad pdpu offset bindings

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Date:   Wed, 25 Jul 2018 10:16:35 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Aapo Vienamo <avienamo@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mikko Perttunen <mperttunen@...dia.com>
Cc:     linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/10] dt-bindings: Add Tegra SDHCI pad pdpu offset
 bindings

On 24.07.2018 17:34, Aapo Vienamo wrote:
> 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@...dia.com>
> ---
>   .../bindings/mmc/nvidia,tegra20-sdhci.txt          | 32 ++++++++++++++++++++++
>   1 file changed, 32 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt b/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
> index 90c214d..949f616 100644
> --- a/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
> +++ b/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt
> @@ -24,6 +24,7 @@ Required properties:
>   Optional properties:
>   - power-gpios : Specify GPIOs for power control
>   
> +Optional properties for Tegra210 and Tegra186:
>   Example:
>   
>   sdhci@...00200 {
> @@ -45,6 +46,33 @@ 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.
> +- pad-autocal-pull-up-offset-3v3, pad-autocal-pull-down-offset-3v3 :
> +  Specify drive strength calibration offsets for 3.3 V signaling modes.
> +- pad-autocal-pull-up-offset-1v8, pad-autocal-pull-down-offset-1v8 :
> +  Specify drive strength calibration offsets for 1.8 V signaling modes.
> +- pad-autocal-pull-up-offset-3v3-timeout,
> +  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.
> +- pad-autocal-pull-up-offset-1v8-timeout,
> +  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.
> +- pad-autocal-pull-up-offset-sdr104,
> +  pad-autocal-pull-down-offset-sdr104 : Specify drive strength
> +  calibration offsets for SDR104 mode.
> +- pad-autocal-pull-up-offset-hs400,
> +  pad-autocal-pull-down-offset-hs400 : Specify drive strength
> +  calibration offsets for HS400 mode.

All of these need an "nvidia," prefix.

> +
> +  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@...b0000 {
> @@ -58,5 +86,9 @@ sdhci@...b0000 {
>   	pinctrl-names = "sdmmc-3v3", "sdmmc-1v8";
>   	pinctrl-0 = <&sdmmc1_3v3>;
>   	pinctrl-1 = <&sdmmc1_1v8>;
> +	pad-autocal-pull-up-offset-3v3 = <0x00>;
> +	pad-autocal-pull-down-offset-3v3 = <0x7d>;
> +	pad-autocal-pull-up-offset-1v8 = <0x7b>;
> +	pad-autocal-pull-down-offset-1v8 = <0x7b>;
>   	status = "disabled";
>   };
>