linux-kernel - Re: [v5 2/4] dt-bindings: mmc: add description of PHY delays for sdhci-cadence

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Message-ID: <CAPDyKFqdEvTHYeLXjD0dsfpNn_jR4DVWYxSNE7KYCPnCdCzTXQ@mail.gmail.com>
Date:   Thu, 30 Mar 2017 21:31:00 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Piotr Sroka <piotrs@...ence.com>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [v5 2/4] dt-bindings: mmc: add description of PHY delays for sdhci-cadence

On 21 March 2017 at 15:33, Piotr Sroka <piotrs@...ence.com> wrote:
> DTS properties are used instead of fixed data
> because PHY settings can be different for different chips/boards.
> Add description of new DLL PHY delays.
>
> Signed-off-by: Piotr Sroka <piotrs@...ence.com>


Thanks, applied for next!

Kind regards
Uffe


> ---
> Changes for v2:
> - file was created in v2. It was a part of driver source file patch.
> - most delays were moved from dts file
>   to data associated with an SoC specific compatible
> - description of delays was updated to be more clearly
> ---
> Changes for v3:
> - move all delays back to dts because they are also boards dependent
> - prefix all of the Cadence-specific properties with cdns prefix
> ---
> Changes for v4:
> - change the beginning of the commit subject
> ---
> Changes for v5:
> - change name of property to be consistent with timing modes
>   available in Linux
> ---
>  .../devicetree/bindings/mmc/sdhci-cadence.txt      | 48 ++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
> index c0f37cb..fa423c2 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
> @@ -19,6 +19,53 @@ if supported.  See mmc.txt for details.
>  - mmc-hs400-1_8v
>  - mmc-hs400-1_2v
>
> +Some PHY delays can be configured by following properties.
> +PHY DLL input delays:
> +They are used to delay the data valid window, and align the window
> +to sampling clock. The delay starts from 5ns (for delay parameter equal to 0)
> +and it is increased by 2.5ns in each step.
> +- cdns,phy-input-delay-sd-highspeed:
> +  Value of the delay in the input path for SD high-speed timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-legacy:
> +  Value of the delay in the input path for legacy timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-sd-uhs-sdr12:
> +  Value of the delay in the input path for SD UHS SDR12 timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-sd-uhs-sdr25:
> +  Value of the delay in the input path for SD UHS SDR25 timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-sd-uhs-sdr50:
> +  Value of the delay in the input path for SD UHS SDR50 timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-sd-uhs-ddr50:
> +  Value of the delay in the input path for SD UHS DDR50 timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-mmc-highspeed:
> +  Value of the delay in the input path for MMC high-speed timing
> +  Valid range = [0:0x1F].
> +- cdns,phy-input-delay-mmc-ddr:
> +  Value of the delay in the input path for eMMC high-speed DDR timing
> +  Valid range = [0:0x1F].
> +
> +PHY DLL clock delays:
> +Each delay property represents the fraction of the clock period.
> +The approximate delay value will be
> +(<delay property value>/128)*sdmclk_clock_period.
> +- cdns,phy-dll-delay-sdclk:
> +  Value of the delay introduced on the sdclk output
> +  for all modes except HS200, HS400 and HS400_ES.
> +  Valid range = [0:0x7F].
> +- cdns,phy-dll-delay-sdclk-hsmmc:
> +  Value of the delay introduced on the sdclk output
> +  for HS200, HS400 and HS400_ES speed modes.
> +  Valid range = [0:0x7F].
> +- cdns,phy-dll-delay-strobe:
> +  Value of the delay introduced on the dat_strobe input
> +  used in HS400 / HS400_ES speed modes.
> +  Valid range = [0:0x7F].
> +
>  Example:
>         emmc: sdhci@...00000 {
>                 compatible = "socionext,uniphier-sd4hc", "cdns,sd4hc";
> @@ -29,4 +76,5 @@ Example:
>                 mmc-ddr-1_8v;
>                 mmc-hs200-1_8v;
>                 mmc-hs400-1_8v;
> +               cdns,phy-dll-delay-sdclk = <0>;
>         };
> --
> 2.2.2
>