All of lore.kernel.org
 help / color / mirror / Atom feed
From: Shawn Guo <shawnguo@kernel.org>
To: Frieder Schrempf <frieder@fris.de>
Cc: Conor Dooley <conor+dt@kernel.org>,
	devicetree@vger.kernel.org,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [PATCH v2 01/14] arm64: dts: imx8mm-kontron: Add support for display bridges on BL i.MX8MM
Date: Wed, 6 Dec 2023 10:34:34 +0800	[thread overview]
Message-ID: <20231206023434.GL236001@dragon> (raw)
In-Reply-To: <20231130161657.556483-2-frieder@fris.de>

On Thu, Nov 30, 2023 at 05:16:01PM +0100, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
> 
> The Kontron Electronics BL i.MX8MM has oboard disply bridges for
> DSI->HDMI and DSI->LVDS conversion. The DSI interface is muxed by
> a GPIO-controlled switch to one of these two bridges.
> 
> By default the HDMI bridge is enabled. The LVDS bridge can be
> selected by loading an additional (panel-specific) overlay.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
> Changes for v2:
> * Rework DSI mux GPIO logic to be compatible with overlay
> * Switch from 4 to 2 DSI lanes for LVDS bridge to fix non-working display
> ---
>  .../boot/dts/freescale/imx8mm-kontron-bl.dts  | 158 ++++++++++++++++++
>  1 file changed, 158 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts b/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> index dcec57c20399e..0fb16b811461e 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> @@ -25,6 +25,17 @@ osc_can: clock-osc-can {
>  		clock-output-names = "osc-can";
>  	};
>  
> +	hdmi-out {
> +		compatible = "hdmi-connector";
> +		type = "a";
> +
> +		port {
> +			hdmi_in_conn: endpoint {
> +				remote-endpoint = <&bridge_out_conn>;
> +			};
> +		};
> +	};
> +
>  	leds {
>  		compatible = "gpio-leds";
>  		pinctrl-names = "default";
> @@ -132,6 +143,102 @@ ethphy: ethernet-phy@0 {
>  	};
>  };
>  
> +&gpio4 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&pinctrl_gpio4>;
> +
> +	dsi_mux_sel_hdmi: dsi-mux-sel-hdmi-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-high;
> +		line-name = "dsi-mux-sel";
> +		status = "okay";

Status "okay" is usually used to flip "disabled".

> +	};
> +
> +	dsi_mux_sel_lvds: dsi-mux-sel-lvds-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "dsi-mux-sel";
> +		status = "disabled";
> +	};
> +
> +	dsi-mux-oe-hog {
> +		gpio-hog;
> +		gpios = <15 GPIO_ACTIVE_LOW>;
> +		output-high;
> +		line-name = "dsi-mux-oe";
> +	};
> +};
> +
> +&i2c3 {
> +	clock-frequency = <400000>;
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&pinctrl_i2c3>;
> +	status = "okay";
> +
> +	hdmi: hdmi@39 {
> +		compatible = "adi,adv7535";
> +		reg = <0x39>;
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_adv7535>;
> +
> +		interrupt-parent = <&gpio4>;
> +		interrupts = <16 IRQ_TYPE_LEVEL_LOW>;
> +
> +		adi,dsi-lanes = <4>;
> +
> +		a2vdd-supply = <&reg_vdd_1v8>;
> +		avdd-supply = <&reg_vdd_1v8>;
> +		dvdd-supply = <&reg_vdd_1v8>;
> +		pvdd-supply = <&reg_vdd_1v8>;
> +		v1p2-supply = <&reg_vdd_1v8>;
> +		v3p3-supply = <&reg_vdd_3v3>;
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;

Have a newline between properties and child node.

Shawn

> +				bridge_in_dsi_hdmi: endpoint {
> +					remote-endpoint = <&dsi_out_bridge>;
> +				};
> +			};
> +
> +			port@1 {
> +				reg = <1>;
> +				bridge_out_conn: endpoint {
> +					remote-endpoint = <&hdmi_in_conn>;
> +				};
> +			};
> +		};
> +	};
> +
> +	lvds: bridge@2c {
> +		compatible = "ti,sn65dsi84";
> +		reg = <0x2c>;
> +		enable-gpios = <&gpio4 26 GPIO_ACTIVE_HIGH>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_sn65dsi84>;
> +		status = "disabled";
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;
> +				bridge_in_dsi_lvds: endpoint {
> +					remote-endpoint = <&dsi_out_bridge>;
> +					data-lanes = <1 2>;
> +				};
> +			};
> +		};
> +	};
> +};
> +
>  &i2c4 {
>  	clock-frequency = <100000>;
>  	pinctrl-names = "default";
> @@ -144,6 +251,30 @@ rx8900: rtc@32 {
>  	};
>  };
>  
> +&lcdif {
> +	status = "okay";
> +};
> +
> +&mipi_dsi {
> +	samsung,esc-clock-frequency = <54000000>;
> +	/*
> +	 * Let the driver calculate an appropriate clock rate based on the pixel
> +	 * clock instead of using the fixed value from imx8mm.dtsi.
> +	 */
> +	/delete-property/ samsung,pll-clock-frequency;
> +	status = "okay";
> +
> +	ports {
> +		port@1 {
> +			reg = <1>;
> +
> +			dsi_out_bridge: endpoint {
> +				remote-endpoint = <&bridge_in_dsi_hdmi>;
> +			};
> +		};
> +	};
> +};
> +
>  &pwm2 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_pwm2>;
> @@ -207,6 +338,12 @@ &iomuxc {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_gpio>;
>  
> +	pinctrl_adv7535: adv7535grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI1_TXD4_GPIO4_IO16		0x19
> +		>;
> +	};
> +
>  	pinctrl_can: cangrp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_SAI3_RXFS_GPIO4_IO28		0x19
> @@ -277,6 +414,20 @@ MX8MM_IOMUXC_SAI3_MCLK_GPIO5_IO2		0x19
>  		>;
>  	};
>  
> +	pinctrl_gpio4: gpio4grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI1_TXD2_GPIO4_IO14		0x19
> +			MX8MM_IOMUXC_SAI1_TXD3_GPIO4_IO15		0x19
> +		>;
> +	};
> +
> +	pinctrl_i2c3: i2c3grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_I2C3_SCL_I2C3_SCL			0x40000083
> +			MX8MM_IOMUXC_I2C3_SDA_I2C3_SDA			0x40000083
> +		>;
> +	};
> +
>  	pinctrl_i2c4: i2c4grp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_I2C4_SCL_I2C4_SCL			0x400001c3
> @@ -290,6 +441,13 @@ MX8MM_IOMUXC_SPDIF_RX_PWM2_OUT			0x19
>  		>;
>  	};
>  
> +	pinctrl_sn65dsi84: sn65dsi84grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI2_TXD0_GPIO4_IO26		0x19
> +			MX8MM_IOMUXC_SD2_WP_GPIO2_IO20			0x19
> +		>;
> +	};
> +
>  	pinctrl_uart1: uart1grp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_SAI2_RXC_UART1_DCE_RX		0x140
> -- 
> 2.43.0
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Shawn Guo <shawnguo@kernel.org>
To: Frieder Schrempf <frieder@fris.de>
Cc: Conor Dooley <conor+dt@kernel.org>,
	devicetree@vger.kernel.org,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [PATCH v2 01/14] arm64: dts: imx8mm-kontron: Add support for display bridges on BL i.MX8MM
Date: Wed, 6 Dec 2023 10:34:34 +0800	[thread overview]
Message-ID: <20231206023434.GL236001@dragon> (raw)
In-Reply-To: <20231130161657.556483-2-frieder@fris.de>

On Thu, Nov 30, 2023 at 05:16:01PM +0100, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
> 
> The Kontron Electronics BL i.MX8MM has oboard disply bridges for
> DSI->HDMI and DSI->LVDS conversion. The DSI interface is muxed by
> a GPIO-controlled switch to one of these two bridges.
> 
> By default the HDMI bridge is enabled. The LVDS bridge can be
> selected by loading an additional (panel-specific) overlay.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
> Changes for v2:
> * Rework DSI mux GPIO logic to be compatible with overlay
> * Switch from 4 to 2 DSI lanes for LVDS bridge to fix non-working display
> ---
>  .../boot/dts/freescale/imx8mm-kontron-bl.dts  | 158 ++++++++++++++++++
>  1 file changed, 158 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts b/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> index dcec57c20399e..0fb16b811461e 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-bl.dts
> @@ -25,6 +25,17 @@ osc_can: clock-osc-can {
>  		clock-output-names = "osc-can";
>  	};
>  
> +	hdmi-out {
> +		compatible = "hdmi-connector";
> +		type = "a";
> +
> +		port {
> +			hdmi_in_conn: endpoint {
> +				remote-endpoint = <&bridge_out_conn>;
> +			};
> +		};
> +	};
> +
>  	leds {
>  		compatible = "gpio-leds";
>  		pinctrl-names = "default";
> @@ -132,6 +143,102 @@ ethphy: ethernet-phy@0 {
>  	};
>  };
>  
> +&gpio4 {
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&pinctrl_gpio4>;
> +
> +	dsi_mux_sel_hdmi: dsi-mux-sel-hdmi-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-high;
> +		line-name = "dsi-mux-sel";
> +		status = "okay";

Status "okay" is usually used to flip "disabled".

> +	};
> +
> +	dsi_mux_sel_lvds: dsi-mux-sel-lvds-hog {
> +		gpio-hog;
> +		gpios = <14 GPIO_ACTIVE_HIGH>;
> +		output-low;
> +		line-name = "dsi-mux-sel";
> +		status = "disabled";
> +	};
> +
> +	dsi-mux-oe-hog {
> +		gpio-hog;
> +		gpios = <15 GPIO_ACTIVE_LOW>;
> +		output-high;
> +		line-name = "dsi-mux-oe";
> +	};
> +};
> +
> +&i2c3 {
> +	clock-frequency = <400000>;
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&pinctrl_i2c3>;
> +	status = "okay";
> +
> +	hdmi: hdmi@39 {
> +		compatible = "adi,adv7535";
> +		reg = <0x39>;
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_adv7535>;
> +
> +		interrupt-parent = <&gpio4>;
> +		interrupts = <16 IRQ_TYPE_LEVEL_LOW>;
> +
> +		adi,dsi-lanes = <4>;
> +
> +		a2vdd-supply = <&reg_vdd_1v8>;
> +		avdd-supply = <&reg_vdd_1v8>;
> +		dvdd-supply = <&reg_vdd_1v8>;
> +		pvdd-supply = <&reg_vdd_1v8>;
> +		v1p2-supply = <&reg_vdd_1v8>;
> +		v3p3-supply = <&reg_vdd_3v3>;
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;

Have a newline between properties and child node.

Shawn

> +				bridge_in_dsi_hdmi: endpoint {
> +					remote-endpoint = <&dsi_out_bridge>;
> +				};
> +			};
> +
> +			port@1 {
> +				reg = <1>;
> +				bridge_out_conn: endpoint {
> +					remote-endpoint = <&hdmi_in_conn>;
> +				};
> +			};
> +		};
> +	};
> +
> +	lvds: bridge@2c {
> +		compatible = "ti,sn65dsi84";
> +		reg = <0x2c>;
> +		enable-gpios = <&gpio4 26 GPIO_ACTIVE_HIGH>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_sn65dsi84>;
> +		status = "disabled";
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;
> +				bridge_in_dsi_lvds: endpoint {
> +					remote-endpoint = <&dsi_out_bridge>;
> +					data-lanes = <1 2>;
> +				};
> +			};
> +		};
> +	};
> +};
> +
>  &i2c4 {
>  	clock-frequency = <100000>;
>  	pinctrl-names = "default";
> @@ -144,6 +251,30 @@ rx8900: rtc@32 {
>  	};
>  };
>  
> +&lcdif {
> +	status = "okay";
> +};
> +
> +&mipi_dsi {
> +	samsung,esc-clock-frequency = <54000000>;
> +	/*
> +	 * Let the driver calculate an appropriate clock rate based on the pixel
> +	 * clock instead of using the fixed value from imx8mm.dtsi.
> +	 */
> +	/delete-property/ samsung,pll-clock-frequency;
> +	status = "okay";
> +
> +	ports {
> +		port@1 {
> +			reg = <1>;
> +
> +			dsi_out_bridge: endpoint {
> +				remote-endpoint = <&bridge_in_dsi_hdmi>;
> +			};
> +		};
> +	};
> +};
> +
>  &pwm2 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_pwm2>;
> @@ -207,6 +338,12 @@ &iomuxc {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_gpio>;
>  
> +	pinctrl_adv7535: adv7535grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI1_TXD4_GPIO4_IO16		0x19
> +		>;
> +	};
> +
>  	pinctrl_can: cangrp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_SAI3_RXFS_GPIO4_IO28		0x19
> @@ -277,6 +414,20 @@ MX8MM_IOMUXC_SAI3_MCLK_GPIO5_IO2		0x19
>  		>;
>  	};
>  
> +	pinctrl_gpio4: gpio4grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI1_TXD2_GPIO4_IO14		0x19
> +			MX8MM_IOMUXC_SAI1_TXD3_GPIO4_IO15		0x19
> +		>;
> +	};
> +
> +	pinctrl_i2c3: i2c3grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_I2C3_SCL_I2C3_SCL			0x40000083
> +			MX8MM_IOMUXC_I2C3_SDA_I2C3_SDA			0x40000083
> +		>;
> +	};
> +
>  	pinctrl_i2c4: i2c4grp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_I2C4_SCL_I2C4_SCL			0x400001c3
> @@ -290,6 +441,13 @@ MX8MM_IOMUXC_SPDIF_RX_PWM2_OUT			0x19
>  		>;
>  	};
>  
> +	pinctrl_sn65dsi84: sn65dsi84grp {
> +		fsl,pins = <
> +			MX8MM_IOMUXC_SAI2_TXD0_GPIO4_IO26		0x19
> +			MX8MM_IOMUXC_SD2_WP_GPIO2_IO20			0x19
> +		>;
> +	};
> +
>  	pinctrl_uart1: uart1grp {
>  		fsl,pins = <
>  			MX8MM_IOMUXC_SAI2_RXC_UART1_DCE_RX		0x140
> -- 
> 2.43.0
> 

  reply	other threads:[~2023-12-06  2:35 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-30 16:16 [PATCH v2 00/14] arm64: dts: imx8mm-kontron: DT updates Frieder Schrempf
2023-11-30 16:16 ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 01/14] arm64: dts: imx8mm-kontron: Add support for display bridges on BL i.MX8MM Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-12-06  2:34   ` Shawn Guo [this message]
2023-12-06  2:34     ` Shawn Guo
2023-12-06 14:46     ` Frieder Schrempf
2023-12-06 14:46       ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 02/14] arm64: dts: imx8mm-kontron: Add DL (Display-Line) overlay with LVDS support Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-12-06  2:43   ` Shawn Guo
2023-12-06  2:43     ` Shawn Guo
2023-12-06 14:48     ` Frieder Schrempf
2023-12-06 14:48       ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 03/14] arm64: dts: imx8mm-kontron: Disable pullups for I2C signals on OSM-S i.MX8MM Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 04/14] arm64: dts: imx8mm-kontron: Disable pullups for I2C signals on SL/BL i.MX8MM Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 05/14] arm64: dts: imx8mm-kontron: Disable pullups for onboard UART signals on BL OSM-S board Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 06/14] arm64: dts: imx8mm-kontron: Disable pullups for onboard UART signals on BL board Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 07/14] arm64: dts: imx8mm-kontron: Disable pull resistors for SD card signals on BL OSM-S board Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 08/14] arm64: dts: imx8mm-kontron: Disable pull resistors for SD card signals on BL board Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 09/14] arm64: dts: imx8mm-kontron: Fix interrupt for RTC on OSM-S i.MX8MM module Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 10/14] arm64: dts: imx8mm-kontron: Fix OSM-S devicetrees to match latest hardware Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 11/14] arm64: dts: imx8mm-kontron: Disable uneffective PUE bit in SDIO IOMUX Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 12/14] arm64: dts: imx8mm-kontron: Remove useless trickle-diode-disable from RTC node Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 13/14] arm64: dts: imx8mm-kontron: Add I2C EEPROM on OSM-S Kontron i.MX8MM Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-11-30 16:16 ` [PATCH v2 14/14] arm64: dts: imx8mm-kontron: Refactor devicetree for OSM-S module and board Frieder Schrempf
2023-11-30 16:16   ` Frieder Schrempf
2023-12-06  3:01   ` Shawn Guo
2023-12-06  3:01     ` Shawn Guo
2023-12-06 14:49     ` Frieder Schrempf
2023-12-06 14:49       ` Frieder Schrempf

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20231206023434.GL236001@dragon \
    --to=shawnguo@kernel.org \
    --cc=conor+dt@kernel.org \
    --cc=devicetree@vger.kernel.org \
    --cc=festevam@gmail.com \
    --cc=frieder.schrempf@kontron.de \
    --cc=frieder@fris.de \
    --cc=kernel@pengutronix.de \
    --cc=krzysztof.kozlowski+dt@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robh+dt@kernel.org \
    --cc=s.hauer@pengutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.