From: Stephan Gerhold <stephan@gerhold.net>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] ARM: dts: ux500: Drop pulls on I2C buses
Date: Tue, 26 Nov 2019 18:59:25 +0100 [thread overview]
Message-ID: <20191126175856.GA12811@gerhold.net> (raw)
In-Reply-To: <20191126123116.56244-1-linus.walleij@linaro.org>
On Tue, Nov 26, 2019 at 01:31:16PM +0100, Linus Walleij wrote:
> The I2C block in the Ux500 uses internal pull-ups on the
> SoC, in fact it has to: in HS mode, the I2C block will need
> to autonomously take control over the pull-up line to do
> its job. This can be clearly seen from the SoC manual which
> states that the silicon has a line named "en_cspu_hs" which
> enables current source pull-up for high speed mode. Another
> hint is that the vendor code tree never enabled the pull
> up on these lines, despite being deployed on boards that
> lack external pull-up resistors.
>
> Tested on the Ux500 reference designs without any problems.
>
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Reported-by: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
FWIW, on samsung,golden:
Tested-by: Stephan Gerhold <stephan@gerhold.net>
> ---
> arch/arm/boot/dts/ste-dbx5x0-pinctrl.dtsi | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/boot/dts/ste-dbx5x0-pinctrl.dtsi b/arch/arm/boot/dts/ste-dbx5x0-pinctrl.dtsi
> index e85a08ad2ea7..7bf7a2d34cbc 100644
> --- a/arch/arm/boot/dts/ste-dbx5x0-pinctrl.dtsi
> +++ b/arch/arm/boot/dts/ste-dbx5x0-pinctrl.dtsi
> @@ -130,7 +130,7 @@
> };
> default_cfg1 {
> pins = "GPIO147_C15", "GPIO148_B16"; /* SDA/SCL */
> - ste,config = <&in_pu>;
> + ste,config = <&in_nopull>;
> };
> };
>
> @@ -150,7 +150,7 @@
> };
> default_cfg1 {
> pins = "GPIO16_AD3", "GPIO17_AD4"; /* SDA/SCL */
> - ste,config = <&in_pu>;
> + ste,config = <&in_nopull>;
> };
> };
>
> @@ -170,7 +170,7 @@
> };
> default_cfg1 {
> pins = "GPIO10_AF5", "GPIO11_AG4"; /* SDA/SCL */
> - ste,config = <&in_pu>;
> + ste,config = <&in_nopull>;
> };
> };
>
> @@ -190,7 +190,7 @@
> };
> default_cfg1 {
> pins = "GPIO229_AG7", "GPIO230_AF7"; /* SDA/SCL */
> - ste,config = <&in_pu>;
> + ste,config = <&in_nopull>;
> };
> };
>
> @@ -214,7 +214,7 @@
> };
> default_cfg1 {
> pins = "GPIO4_AH6", "GPIO5_AG6"; /* SDA/SCL */
> - ste,config = <&in_pu>;
> + ste,config = <&in_nopull>;
> };
> };
>
> --
> 2.23.0
>
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prev parent reply other threads:[~2019-11-26 17:59 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 12:31 [PATCH] ARM: dts: ux500: Drop pulls on I2C buses Linus Walleij
2019-11-26 17:59 ` Stephan Gerhold [this message]
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