The imx8mm-venice-gw73xx-0x som+baseboard combination has a multi-protocol
RS-232/RS-485/RS-422 transceiver to an off-board connector which
can be configured in a number of ways via UART and GPIO configuration.
The default configuration per the imx8mm-venice-gw73xx-0x dts is for
UART2 TX/RX and UART4 TX/RX to be available as RS-232:
J15.1 UART2 TX out
J15.2 UART2 RX in
J15.3 UART4 TX out
J15.4 UART4 RX in
J15.5 GND
Add dt overlays to allow additional the modes of operation:
rs232-rts (UART2 RS-232 with RTS/CTS hardware flow control)
J15.1 TX out
J15.2 RX in
J15.3 RTS out
J15.4 CTS in
J15.5 GND
rs485 (UART2 RS-485 half duplex)
J15.1 TXRX-
J15.2 N/C
J15.3 TXRX+
J15.4 N/C
J15.5 GND
rs422 (UART2 RS-422 full duplex)
J15.1 TX-
J15.2 RX+
J15.3 TX+
J15.4 RX-
J15.5 GND
Signed-off-by: Tim Harvey <[email protected]>
---
arch/arm64/boot/dts/freescale/Makefile | 3 +
.../imx8mm-venice-gw73xx-0x-rs232-rts.dts | 53 ++++++++++++++++
.../imx8mm-venice-gw73xx-0x-rs422.dts | 61 +++++++++++++++++++
.../imx8mm-venice-gw73xx-0x-rs485.dts | 61 +++++++++++++++++++
4 files changed, 178 insertions(+)
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
index a14a6173b765..5ec8d59347b6 100644
--- a/arch/arm64/boot/dts/freescale/Makefile
+++ b/arch/arm64/boot/dts/freescale/Makefile
@@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
new file mode 100644
index 000000000000..c184cf4aea4e
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2021 Gateworks Corporation
+ *
+ * GW73xx RS232 with RTS/CTS hardware flow control:
+ * - GPIO4_0 rs485_en needs to be driven low (in-active)
+ * - UART4_TX becomes RTS
+ * - UART4_RX becomes CTS
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw73xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-low;
+ line-name = "rs485_en";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_LOW>;
+ cts-gpios = <&gpio5 28 GPIO_ACTIVE_LOW>;
+ uart-has-rtscts;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uart2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ MX8MM_IOMUXC_UART4_RXD_GPIO5_IO28 0x140
+ >;
+ };
+};
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
new file mode 100644
index 000000000000..3e6404340d52
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2021 Gateworks Corporation
+ *
+ * GW73xx RS422 (RS485 full duplex):
+ * - GPIO1_0 rs485_term selects on-chip termination
+ * - GPIO4_0 rs485_en needs to be driven high (active)
+ * - GPIO4_2 rs485_hd needs to be driven low (in-active)
+ * - UART4_TX is DE for RS485 transmitter
+ * - RS485_EN needs to be pulled high
+ * - RS485_HALF needs to be low
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw73xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_en";
+ };
+
+ rs485_hd {
+ gpio-hog;
+ gpios = <2 GPIO_ACTIVE_HIGH>;
+ output-low;
+ line-name = "rs485_hd";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
+ linux,rs485-enabled-at-boot-time;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uart2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ >;
+ };
+};
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
new file mode 100644
index 000000000000..97f19c15c3d0
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2021 Gateworks Corporation
+ *
+ * GW73xx RS485 HD:
+ * - GPIO1_0 rs485_term selects on-chip termination
+ * - GPIO4_0 rs485_en needs to be driven high (active)
+ * - GPIO4_2 rs485_hd needs to be driven high (active)
+ * - UART4_TX is DE for RS485 transmitter
+ * - RS485_EN needs to be pulled high
+ * - RS485_HALF needs to be pulled high
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw73xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_en";
+ };
+
+ rs485_hd {
+ gpio-hog;
+ gpios = <2 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_hd";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
+ linux,rs485-enabled-at-boot-time;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uast2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ >;
+ };
+};
--
2.17.1
On Tue, Dec 14, 2021 at 1:36 PM Tim Harvey <[email protected]> wrote:
>
> The imx8mm-venice-gw73xx-0x som+baseboard combination has a multi-protocol
> RS-232/RS-485/RS-422 transceiver to an off-board connector which
> can be configured in a number of ways via UART and GPIO configuration.
>
> The default configuration per the imx8mm-venice-gw73xx-0x dts is for
> UART2 TX/RX and UART4 TX/RX to be available as RS-232:
> J15.1 UART2 TX out
> J15.2 UART2 RX in
> J15.3 UART4 TX out
> J15.4 UART4 RX in
> J15.5 GND
>
> Add dt overlays to allow additional the modes of operation:
>
> rs232-rts (UART2 RS-232 with RTS/CTS hardware flow control)
> J15.1 TX out
> J15.2 RX in
> J15.3 RTS out
> J15.4 CTS in
> J15.5 GND
>
> rs485 (UART2 RS-485 half duplex)
> J15.1 TXRX-
> J15.2 N/C
> J15.3 TXRX+
> J15.4 N/C
> J15.5 GND
>
> rs422 (UART2 RS-422 full duplex)
> J15.1 TX-
> J15.2 RX+
> J15.3 TX+
> J15.4 RX-
> J15.5 GND
>
> Signed-off-by: Tim Harvey <[email protected]>
> ---
> arch/arm64/boot/dts/freescale/Makefile | 3 +
> .../imx8mm-venice-gw73xx-0x-rs232-rts.dts | 53 ++++++++++++++++
> .../imx8mm-venice-gw73xx-0x-rs422.dts | 61 +++++++++++++++++++
> .../imx8mm-venice-gw73xx-0x-rs485.dts | 61 +++++++++++++++++++
> 4 files changed, 178 insertions(+)
> create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
> create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
> create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
>
> diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
> index a14a6173b765..5ec8d59347b6 100644
> --- a/arch/arm64/boot/dts/freescale/Makefile
> +++ b/arch/arm64/boot/dts/freescale/Makefile
> @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
> dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
> new file mode 100644
> index 000000000000..c184cf4aea4e
> --- /dev/null
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dts
> @@ -0,0 +1,53 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright 2021 Gateworks Corporation
> + *
> + * GW73xx RS232 with RTS/CTS hardware flow control:
> + * - GPIO4_0 rs485_en needs to be driven low (in-active)
> + * - UART4_TX becomes RTS
> + * - UART4_RX becomes CTS
> + */
> +
> +#include <dt-bindings/gpio/gpio.h>
> +
> +#include "imx8mm-pinfunc.h"
> +
> +/dts-v1/;
> +/plugin/;
> +
> +&{/} {
> + compatible = "gw,imx8mm-gw73xx-0x";
> +};
> +
> +&gpio4 {
> + rs485_en {
> + gpio-hog;
> + gpios = <0 GPIO_ACTIVE_HIGH>;
> + output-low;
> + line-name = "rs485_en";
> + };
> +};
> +
> +&uart2 {
> + pinctrl-names = "default";
> + pinctrl-0 = <&pinctrl_uart2>;
> + rts-gpios = <&gpio5 29 GPIO_ACTIVE_LOW>;
> + cts-gpios = <&gpio5 28 GPIO_ACTIVE_LOW>;
> + uart-has-rtscts;
> + status = "okay";
> +};
> +
> +&uart4 {
> + status = "disabled";
> +};
> +
> +&iomuxc {
> + pinctrl_uart2: uart2grp {
> + fsl,pins = <
> + MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
> + MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
> + MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
> + MX8MM_IOMUXC_UART4_RXD_GPIO5_IO28 0x140
> + >;
> + };
> +};
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
> new file mode 100644
> index 000000000000..3e6404340d52
> --- /dev/null
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dts
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright 2021 Gateworks Corporation
> + *
> + * GW73xx RS422 (RS485 full duplex):
> + * - GPIO1_0 rs485_term selects on-chip termination
> + * - GPIO4_0 rs485_en needs to be driven high (active)
> + * - GPIO4_2 rs485_hd needs to be driven low (in-active)
> + * - UART4_TX is DE for RS485 transmitter
> + * - RS485_EN needs to be pulled high
> + * - RS485_HALF needs to be low
> + */
> +
> +#include <dt-bindings/gpio/gpio.h>
> +
> +#include "imx8mm-pinfunc.h"
> +
> +/dts-v1/;
> +/plugin/;
> +
> +&{/} {
> + compatible = "gw,imx8mm-gw73xx-0x";
> +};
> +
> +&gpio4 {
> + rs485_en {
> + gpio-hog;
> + gpios = <0 GPIO_ACTIVE_HIGH>;
> + output-high;
> + line-name = "rs485_en";
> + };
> +
> + rs485_hd {
> + gpio-hog;
> + gpios = <2 GPIO_ACTIVE_HIGH>;
> + output-low;
> + line-name = "rs485_hd";
> + };
> +};
> +
> +&uart2 {
> + pinctrl-names = "default";
> + pinctrl-0 = <&pinctrl_uart2>;
> + rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
> + linux,rs485-enabled-at-boot-time;
> + status = "okay";
> +};
> +
> +&uart4 {
> + status = "disabled";
> +};
> +
> +&iomuxc {
> + pinctrl_uart2: uart2grp {
> + fsl,pins = <
> + MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
> + MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
> + MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
> + >;
> + };
> +};
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
> new file mode 100644
> index 000000000000..97f19c15c3d0
> --- /dev/null
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dts
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright 2021 Gateworks Corporation
> + *
> + * GW73xx RS485 HD:
> + * - GPIO1_0 rs485_term selects on-chip termination
> + * - GPIO4_0 rs485_en needs to be driven high (active)
> + * - GPIO4_2 rs485_hd needs to be driven high (active)
> + * - UART4_TX is DE for RS485 transmitter
> + * - RS485_EN needs to be pulled high
> + * - RS485_HALF needs to be pulled high
> + */
> +
> +#include <dt-bindings/gpio/gpio.h>
> +
> +#include "imx8mm-pinfunc.h"
> +
> +/dts-v1/;
> +/plugin/;
> +
> +&{/} {
> + compatible = "gw,imx8mm-gw73xx-0x";
> +};
> +
> +&gpio4 {
> + rs485_en {
> + gpio-hog;
> + gpios = <0 GPIO_ACTIVE_HIGH>;
> + output-high;
> + line-name = "rs485_en";
> + };
> +
> + rs485_hd {
> + gpio-hog;
> + gpios = <2 GPIO_ACTIVE_HIGH>;
> + output-high;
> + line-name = "rs485_hd";
> + };
> +};
> +
> +&uart2 {
> + pinctrl-names = "default";
> + pinctrl-0 = <&pinctrl_uart2>;
> + rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
> + linux,rs485-enabled-at-boot-time;
> + status = "okay";
> +};
> +
> +&uart4 {
> + status = "disabled";
> +};
> +
> +&iomuxc {
> + pinctrl_uart2: uast2grp {
> + fsl,pins = <
> + MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
> + MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
> + MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
> + >;
> + };
> +};
> --
> 2.17.1
>
gentle ping.
I'm mostly interested to see if my approach to dt fragments here and
the naming of the files makes sense to others.
This patch causes the kernel to build dtbo files for:
arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
The intention is that these files are used by boot firmware (U-Boot)
to adjust the dtb before passing it to the kernel.
Best regards,
Tim
Am Dienstag, 11. Januar 2022, 01:00:21 CET schrieb Tim Harvey:
> [SNIP]
> > diff --git a/arch/arm64/boot/dts/freescale/Makefile
> > b/arch/arm64/boot/dts/freescale/Makefile index a14a6173b765..5ec8d59347b6
> > 100644
> > --- a/arch/arm64/boot/dts/freescale/Makefile
> > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
> >
> > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> >
> > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> >
> > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> > dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> >
> [SNIP]
> I'm mostly interested to see if my approach to dt fragments here and
> the naming of the files makes sense to others.
>
> This patch causes the kernel to build dtbo files for:
> arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
> arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
>
> The intention is that these files are used by boot firmware (U-Boot)
> to adjust the dtb before passing it to the kernel.
Hi Tim,
do these dtbo actually work? I'm wondering because I was trying to useoverlays
myself and noticed that the had to be compiled with -@ for u-boot to be able
to apply them. Apparently there are 2 possibilities:
* Set "DTC_FLAGS_[dtb] := -@" yourself
See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
commit/?id=e426d63e752bdbe7d5ba2d872319dde9ab844a07
* Use dedicated overlay target
See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
commit/?id=15d16d6dadf6947ac7f9a686c615995c5a426ce2
You use neither of them. IIRC just naming the target file .dtbo will not apply
symbols (-Q) during dtc call. Can you verify using 'V=1'
Also I'm wondering which way is the best to go.
Best regards,
Alexander
On Mon, Jan 10, 2022 at 11:20 PM Alexander Stein
<[email protected]> wrote:
>
> Am Dienstag, 11. Januar 2022, 01:00:21 CET schrieb Tim Harvey:
> > [SNIP]
> > > diff --git a/arch/arm64/boot/dts/freescale/Makefile
> > > b/arch/arm64/boot/dts/freescale/Makefile index a14a6173b765..5ec8d59347b6
> > > 100644
> > > --- a/arch/arm64/boot/dts/freescale/Makefile
> > > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > > @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
> > >
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> > >
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> > >
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> > >
> > [SNIP]
> > I'm mostly interested to see if my approach to dt fragments here and
> > the naming of the files makes sense to others.
> >
> > This patch causes the kernel to build dtbo files for:
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
> >
> > The intention is that these files are used by boot firmware (U-Boot)
> > to adjust the dtb before passing it to the kernel.
>
> Hi Tim,
>
> do these dtbo actually work? I'm wondering because I was trying to useoverlays
> myself and noticed that the had to be compiled with -@ for u-boot to be able
> to apply them. Apparently there are 2 possibilities:
Alexander,
Yes, they work, but I do manually set DTC_FLAGS=-@ when building
kernel dtbs to make them work.
> * Set "DTC_FLAGS_[dtb] := -@" yourself
> See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> commit/?id=e426d63e752bdbe7d5ba2d872319dde9ab844a07
>
> * Use dedicated overlay target
> See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> commit/?id=15d16d6dadf6947ac7f9a686c615995c5a426ce2
>
> You use neither of them. IIRC just naming the target file .dtbo will not apply
> symbols (-Q) during dtc call. Can you verify using 'V=1'
> Also I'm wondering which way is the best to go.
>
I wasn't aware there was a way to do this via Makefiles. It seems that
perhaps Rob's approach with 'kbuild: Add generic rule to apply
fdtoverlay' is a way to avoid having to add them all manually in the
first approach? I must admit I'm not sure how to use that.
Best regards,
Tim
Am Dienstag, 11. Januar 2022, 18:53:29 CET schrieb Tim Harvey:
> On Mon, Jan 10, 2022 at 11:20 PM Alexander Stein
>
> <[email protected]> wrote:
> > Am Dienstag, 11. Januar 2022, 01:00:21 CET schrieb Tim Harvey:
> > > [SNIP]
> > >
> > > > diff --git a/arch/arm64/boot/dts/freescale/Makefile
> > > > b/arch/arm64/boot/dts/freescale/Makefile index
> > > > a14a6173b765..5ec8d59347b6
> > > > 100644
> > > > --- a/arch/arm64/boot/dts/freescale/Makefile
> > > > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > > > @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) +=
> > > > imx8mm-var-som-symphony.dtb
> > > >
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> > > >
> > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> > > >
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> > > > dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> > >
> > > [SNIP]
> > > I'm mostly interested to see if my approach to dt fragments here and
> > > the naming of the files makes sense to others.
> > >
> > > This patch causes the kernel to build dtbo files for:
> > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
> > >
> > > The intention is that these files are used by boot firmware (U-Boot)
> > > to adjust the dtb before passing it to the kernel.
> >
> > Hi Tim,
> >
> > do these dtbo actually work? I'm wondering because I was trying to
> > useoverlays myself and noticed that the had to be compiled with -@ for
> > u-boot to be able
> > to apply them. Apparently there are 2 possibilities:
> Alexander,
>
> Yes, they work, but I do manually set DTC_FLAGS=-@ when building
> kernel dtbs to make them work.
I see, I expected something like this. That's why I responded to you.
> > * Set "DTC_FLAGS_[dtb] := -@" yourself
> > See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> > commit/?id=e426d63e752bdbe7d5ba2d872319dde9ab844a07
> >
> > * Use dedicated overlay target
> > See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> > commit/?id=15d16d6dadf6947ac7f9a686c615995c5a426ce2
> >
> > You use neither of them. IIRC just naming the target file .dtbo will not
> > apply symbols (-Q) during dtc call. Can you verify using 'V=1'
> > Also I'm wondering which way is the best to go.
>
> I wasn't aware there was a way to do this via Makefiles. It seems that
> perhaps Rob's approach with 'kbuild: Add generic rule to apply
> fdtoverlay' is a way to avoid having to add them all manually in the
> first approach? I must admit I'm not sure how to use that.
I tried using this myself for my custom board. I feel it is a bit cumbersome
to get it right.
See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/
arch/arm64/boot/dts/xilinx/Makefile for an example.
Essentially you define your .dtb as before and add another target (e.g. sm-
k26-revA-sck-kv-g-revA-dtbs) where you add your .dtbo _after_ the original
.dtb. This target needs to be added to 'dtb-y' as before.
I suspect this way is needed to check the .dtbo against the base .dtb if it
actually matches.
HTH
Alexander
On Wed, Jan 12, 2022 at 07:58:00AM +0100, Alexander Stein wrote:
> Am Dienstag, 11. Januar 2022, 18:53:29 CET schrieb Tim Harvey:
> > On Mon, Jan 10, 2022 at 11:20 PM Alexander Stein
> >
> > <[email protected]> wrote:
> > > Am Dienstag, 11. Januar 2022, 01:00:21 CET schrieb Tim Harvey:
> > > > [SNIP]
> > > >
> > > > > diff --git a/arch/arm64/boot/dts/freescale/Makefile
> > > > > b/arch/arm64/boot/dts/freescale/Makefile index
> > > > > a14a6173b765..5ec8d59347b6
> > > > > 100644
> > > > > --- a/arch/arm64/boot/dts/freescale/Makefile
> > > > > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > > > > @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) +=
> > > > > imx8mm-var-som-symphony.dtb
> > > > >
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> > > > >
> > > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> > > > >
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> > > > > dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> > > >
> > > > [SNIP]
> > > > I'm mostly interested to see if my approach to dt fragments here and
> > > > the naming of the files makes sense to others.
> > > >
> > > > This patch causes the kernel to build dtbo files for:
> > > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
> > > >
> > > > The intention is that these files are used by boot firmware (U-Boot)
> > > > to adjust the dtb before passing it to the kernel.
> > >
> > > Hi Tim,
> > >
> > > do these dtbo actually work? I'm wondering because I was trying to
> > > useoverlays myself and noticed that the had to be compiled with -@ for
> > > u-boot to be able
> > > to apply them. Apparently there are 2 possibilities:
> > Alexander,
> >
> > Yes, they work, but I do manually set DTC_FLAGS=-@ when building
> > kernel dtbs to make them work.
>
> I see, I expected something like this. That's why I responded to you.
>
> > > * Set "DTC_FLAGS_[dtb] := -@" yourself
> > > See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> > > commit/?id=e426d63e752bdbe7d5ba2d872319dde9ab844a07
> > >
> > > * Use dedicated overlay target
> > > See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> > > commit/?id=15d16d6dadf6947ac7f9a686c615995c5a426ce2
> > >
> > > You use neither of them. IIRC just naming the target file .dtbo will not
> > > apply symbols (-Q) during dtc call. Can you verify using 'V=1'
> > > Also I'm wondering which way is the best to go.
> >
> > I wasn't aware there was a way to do this via Makefiles. It seems that
> > perhaps Rob's approach with 'kbuild: Add generic rule to apply
> > fdtoverlay' is a way to avoid having to add them all manually in the
> > first approach? I must admit I'm not sure how to use that.
>
> I tried using this myself for my custom board. I feel it is a bit cumbersome
> to get it right.
> See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/
> arch/arm64/boot/dts/xilinx/Makefile for an example.
>
> Essentially you define your .dtb as before and add another target (e.g. sm-
> k26-revA-sck-kv-g-revA-dtbs) where you add your .dtbo _after_ the original
> .dtb. This target needs to be added to 'dtb-y' as before.
>
> I suspect this way is needed to check the .dtbo against the base .dtb if it
> actually matches.
Yeah, I like this check. Tim, could you update your patch to follow
this pattern?
Shawn