On Thu, Dec 19, 2024 at 08:25:27AM +0100, Ahmad Fatoum wrote:
> The HDMI DDC pads can be muxed either to an i.MX I2C controller or
> to a limited I2C controller within the Designware HDMI bridge.
>
> So far we muxed the pads to the HDMI bridge, but the i.MX I2C controller
> is the better choice:
Switch to the i.MX I2C controller because
>
> - We use DDC/CI commands for display brightness configuration, but the
> Linux driver refuses[1] transfers to/from address 0x37, because the
> controller doesn't support multi-byte requests.
Designware HDMI Limited I2C controller doesn't support multi-byte
requests and display brightness configuration by DDC/CI command need it.
>
> - The driver doesn't support I2C bus recovery, but we need that,
> because some HDMI panels used with the board can be flaky.
Designware HDMI Limited I2C controller doesn't support I2C bus
recovery.
>
> As the i.MX I2C controller doesn't have either of these limitations,
> let's make use of it instead.
Reduntant. can be removed.
Frank
>
> [1]: https://lore.kernel.org/all/20190722181945.244395-1-mka@xxxxxxxxxxxx/
>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> .../boot/dts/freescale/imx8mp-skov-revb-hdmi.dts | 26 ++++++++++++++++++++--
> 1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts b/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
> index c1ca69da3cb8..206116be8166 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mp-skov-revb-hdmi.dts
> @@ -9,12 +9,34 @@ / {
> compatible = "skov,imx8mp-skov-revb-hdmi", "fsl,imx8mp";
> };
>
> +&i2c5 {
> + pinctrl-names = "default", "gpio";
> + pinctrl-0 = <&pinctrl_i2c5>;
> + pinctrl-1 = <&pinctrl_i2c5_gpio>;
> + scl-gpios = <&gpio3 26 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> + sda-gpios = <&gpio3 27 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> + clock-frequency = <100000>;
> + status = "okay";
> +};
> +
> &iomuxc {
> pinctrl_hdmi: hdmigrp {
> fsl,pins = <
> - MX8MP_IOMUXC_HDMI_DDC_SCL__HDMIMIX_HDMI_SCL 0x1c3
> - MX8MP_IOMUXC_HDMI_DDC_SDA__HDMIMIX_HDMI_SDA 0x1c3
> MX8MP_IOMUXC_HDMI_HPD__HDMIMIX_HDMI_HPD 0x19
> >;
> };
> +
> + pinctrl_i2c5: i2c5grp {
> + fsl,pins = <
> + MX8MP_IOMUXC_HDMI_DDC_SCL__I2C5_SCL 0x400001c2
> + MX8MP_IOMUXC_HDMI_DDC_SDA__I2C5_SDA 0x400001c2
> + >;
> + };
> +
> + pinctrl_i2c5_gpio: i2c5gpiogrp {
> + fsl,pins = <
> + MX8MP_IOMUXC_HDMI_DDC_SCL__GPIO3_IO26 0x400001c2
> + MX8MP_IOMUXC_HDMI_DDC_SDA__GPIO3_IO27 0x400001c2
> + >;
> + };
> };
>
> --
> 2.39.5
>
