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References: <20211112183311.9556-1-tharvey@gateworks.com> <YZIsa6F0ijVRDvAV@pendragon.ideasonboard.com>
In-Reply-To: <YZIsa6F0ijVRDvAV@pendragon.ideasonboard.com>
From:   Tim Harvey <tharvey@gateworks.com>
Date:   Mon, 15 Nov 2021 10:06:06 -0800
Message-ID: <CAJ+vNU1d2REruejA2nX=PQmm1Leps6NX5csjmLwZe2y1ST7Kng@mail.gmail.com>
Subject: Re: [RFC] arm64: dts: imx8mm: add imx8mm-venice-gw73xx-0x-imx219 overlay
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     Device Tree Mailing List <devicetree@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        open list <linux-kernel@vger.kernel.org>,
        Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
        Adam Ford <aford173@gmail.com>
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Precedence: bulk

On Mon, Nov 15, 2021 at 1:46 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Tim,
>
> Thank you for the patch.

Laurent,

Thanks for the review.

>
> On Fri, Nov 12, 2021 at 10:33:11AM -0800, Tim Harvey wrote:
> > Add support for the RaspberryPi Camera v2 module attached to an
> > imx8mm-venice-gw73xx-0x.
> >
> > This camera is an IMX219 8MP module:
> >  - https://datasheets.raspberrypi.com/camera/camera-v2-schematics.pdf
> >  - has its own on-board 24MHz osc so no clock required from baseboard
> >  - pin 11 enables 1.8V and 2.8V LDO which is connected to
> >    GW73xx MIPI_GPIO4 (IMX8MM GPIO1_IO1). The imx219 driver does not
> >    support powerdown-gpios therefore we use gpio1 via reset-gpios
>
> How about modeling this with a GPIO-controlled regulator, and connecting
> it to the IMX219 through the *-supply properties ?

Sure... that is probably more appropriate.

>
> > Support is added via a device-tree overlay.
> >
> > The IMX219 supports RAW8/RAW10 image formats.
> >
> > Example usage:
> >  media-ctl --links "'imx219 2-0010':0->'imx7-mipi-csis.0':0[1]"
> >  media-ctl -v -V "'imx219 2-0010':0 [fmt:SRGGB8/640x480 field:none]"
> >  media-ctl -v -V "'csi':0 [fmt:SRGGB8/640x480 field:none]"
> >  gst-launch-1.0 -v v4l2src num-buffers=1 ! \
> >        video/x-bayer,format=rggb,width=640,height=480,framerate=30/1 ! \
> >        bayer2rgb ! jpegenc ! filesink location=test.jpg
> >  gst-launch-1.0 -v v4l2src num-buffers=300 ! \
> >        video/x-bayer,format=rggb,width=640,height=480,framerate=30/1 ! \
> >        bayer2rgb ! jpegenc ! avimux ! filesink location=test.avi
> >
> > This patch depends on 'arm64: dts: imx8mm: Add CSI nodes' at:
> > https://lore.kernel.org/all/20211106155427.753197-2-aford173@gmail.com/
> >
> > This is an RFC as I am not aware of other dt fragments/overlays being
> > added to the kernel yet. I do get a few warnings but I believe they are
> > because this is a fragment:
>
> I like the idea of centralizing DT overlays. I'm not sure where to best
> store them, and I don't know if this has been discussed already, but the
> kernel supports compilation of DT overlays, so I assume it's meant to be
> used. Rob may have an opinion on this.

My understanding is that DT overlays are typically .dtbo vs .dtb but I
noticed the kernel Makefiles did not have support for this. I do feel
the DT overlays should be in the kernel tree as they apply to the DT's
there as well.

>
> What we're really missing is a way to parametrize DT overlays, so that a
> single overlay file could be used with different hosts. Discussions
> about DT connectors have died out as far as I know, but they were aiming
> at overlays being applied at runtime. I'm not aware of a similar effort
> to standardize connectors when applying overlays in the boot loader. The
> Raspberry Pi boot loader has a proprietary implementation of this
> feature, which is very handy.
>

I like the idea as this particular overlay would also apply to
imx8mm-venice-gw72xx-0x and I would otherwise have to have a duplicate
of it for that board.

The other reason I want to solve this with a DT overlay is that both
'imx8mm-venice-gw73xx-0x' and 'imx8mm-venice-gw72xx-0x' have the
following DT overlays that I'm working on:
- rs232-rts (not sure the best name for this but the default is to
have UART2/UART4 TX/RX RS232 only and this DT overlay would drop UART4
and make UART2 have RTS/CTS hardware flow control instead)
- rs485 (would drop UART4 and make UART2 rs485 half duplex)
- rs422 (would drop UART4 and make UART2 rs422 full duplex)
- rpidsi (not sure the best name for this; would add support for
RaspberryPi 5in and 7in DSI touchscreen displays)
- imx219 (this patch; not sure the best name for this; would add
support for RaspberryPi v2.0 camera sensor)

All of the above overlays would be available for both boards which
would create a lot of combinations if I were to create upper level non
overlay dts files for them.

Best regards,

Tim

> > $ make DTC_FLAGS="-@" dtbs W=1
> >   DTC
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts:33.3-16:
> > Warning (reg_format): /fragment@2/__overlay__/sensor@10:reg: property
> > has invalid length (4 bytes) (#address-cells == 2, #size-cells == 1)
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts:52.10-57.5:
> > Warning (unit_address_vs_reg): /fragment@3/__overlay__/ports/port@0:
> > node has a unit name, but no reg or ranges property
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (pci_device_reg): Failed prerequisite 'reg_format'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (pci_device_bus_num): Failed prerequisite 'reg_format'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (simple_bus_reg): Failed prerequisite 'reg_format'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (i2c_bus_reg): Failed prerequisite 'reg_format'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (spi_bus_reg): Failed prerequisite 'reg_format'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts:29.20-46.4:
> > Warning (avoid_default_addr_size): /fragment@2/__overlay__/sensor@10:
> > Relying on default #address-cells value
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts:29.20-46.4:
> > Warning (avoid_default_addr_size): /fragment@2/__overlay__/sensor@10:
> > Relying on default #size-cells value
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (avoid_unnecessary_addr_size): Failed prerequisite
> > 'avoid_default_addr_size'
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dtb:
> > Warning (unique_unit_address): Failed prerequisite
> > 'avoid_default_addr_size'
> >
> > The intended use of a dt fragement like this is to apply it in boot
> > firmware before booting the kernel such as:
> >
> > u-boot=> load mmc 0:1 $fdt_addr_r imx8mm-venice-gw73xx-0x.dtb
> > u-boot=> fdt addr $fdt_addr_r
> > u-boot=> fdt resize
> > u-boot=> load mmc 0:1 $loadaddr imx8mm-venice-gw73xx-0x-imx219.dtb
> > u-boot=> fdt appply $loadaddr
> > u-boot=> load mmc 0:1 $kernel_addr_r Image
> > u-boot=> booti $kernel_addr_r - $fdt_addr_r
> >
> > Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> > ---
> >  arch/arm64/boot/dts/freescale/Makefile        |  1 +
> >  .../imx8mm-venice-gw73xx-0x-imx219.dts        | 67 +++++++++++++++++++
> >  2 files changed, 68 insertions(+)
> >  create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts
> >
> > diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
> > index db9e36ebe932..cc00ac78dbc6 100644
> > --- a/arch/arm64/boot/dts/freescale/Makefile
> > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > @@ -42,6 +42,7 @@ dtb-$(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-imx219.dtb
> >  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-imx219.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts
> > new file mode 100644
> > index 000000000000..6f692ba24a31
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-imx219.dts
> > @@ -0,0 +1,67 @@
> > +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> > +/*
> > + * Copyright 2021 Gateworks Corporation
> > + */
> > +
> > +#include <dt-bindings/gpio/gpio.h>
> > +
> > +#include "imx8mm-pinfunc.h"
> > +
> > +/dts-v1/;
> > +/plugin/;
> > +
> > +&{/} {
> > +     compatible = "gw,imx8mm-gw73xx-0x", "fsl,imx8mm";
> > +
> > +     cam24m: cam24m {
> > +             compatible = "fixed-clock";
> > +             #clock-cells = <0>;
> > +             clock-frequency = <24000000>;
> > +             clock-output-names = "cam24m";
> > +     };
> > +};
> > +
> > +&csi {
> > +     status = "okay";
> > +};
> > +
> > +&i2c3 {
> > +     imx219: sensor@10 {
> > +             compatible = "sony,imx219";
> > +             pinctrl-names = "default";
> > +             pinctrl-0 = <&pinctrl_imx219>;
> > +             reg = <0x10>;
> > +             clocks = <&cam24m>;
> > +             reset-gpios = <&gpio1 1 GPIO_ACTIVE_HIGH>;
> > +
> > +             port {
> > +                     /* MIPI CSI-2 bus endpoint */
> > +                     imx219_to_mipi_csi2: endpoint {
> > +                             remote-endpoint = <&imx8mm_mipi_csi_in>;
> > +                             clock-lanes = <0>;
> > +                             data-lanes = <1 2>;
> > +                             link-frequencies = /bits/ 64 <456000000>;
> > +                     };
> > +             };
> > +     };
> > +};
> > +
> > +&mipi_csi {
> > +     status = "okay";
> > +     ports {
> > +             port@0 {
> > +                     imx8mm_mipi_csi_in: endpoint {
> > +                             remote-endpoint = <&imx219_to_mipi_csi2>;
> > +                             data-lanes = <1 2>;
> > +                     };
> > +             };
> > +     };
> > +};
> > +
> > +&iomuxc {
> > +     pinctrl_imx219: imx219grp {
> > +             fsl,pins = <
> > +                     MX8MM_IOMUXC_GPIO1_IO01_GPIO1_IO1       0x41
> > +             >;
> > +     };
> > +};
>
> --
> Regards,
>
> Laurent Pinchart