Subject: Re: [RFC PATCH v2 5/7] ARM: dts: bcm2711: Add unicam CSI nodes

From: Laurent Pinchart <[email-masked]>
Date: Wed, 26 Jan 2022 20:42:44 +0200

Hi Dave,

On Mon, Jan 24, 2022 at 12:31:34PM +0000, Dave Stevenson wrote:
> On Fri, 21 Jan 2022 at 22:45, Laurent Pinchart wrote:
> > On Fri, Jan 21, 2022 at 09:18:08AM +0100, Jean-Michel Hautbois wrote:
> > > Add both MIPI CSI-2 nodes in the core bcm2711 tree. Use the 3-cells
> > > interrupt declaration, corresponding clocks and default as disabled.
> > >
> > > Signed-off-by: Jean-Michel Hautbois <[email-masked]>
> > > ---
> > >  arch/arm/boot/dts/bcm2711.dtsi | 31 +++++++++++++++++++++++++++++++
> > >  1 file changed, 31 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
> > > index dff18fc9a906..077141df7024 100644
> > > --- a/arch/arm/boot/dts/bcm2711.dtsi
> > > +++ b/arch/arm/boot/dts/bcm2711.dtsi
> > > @@ -3,6 +3,7 @@
> > >
> > >  #include <dt-bindings/interrupt-controller/arm-gic.h>
> > >  #include <dt-bindings/soc/bcm2835-pm.h>
> > > +#include <dt-bindings/power/raspberrypi-power.h>
> > >
> > >  / {
> > >       compatible = "brcm,bcm2711";
> > > @@ -293,6 +294,36 @@ hvs: hvs@7e400000 {
> > >                       interrupts = <GIC_SPI 97 IRQ_TYPE_LEVEL_HIGH>;
> > >               };
> > >
> > > +             csi0: csi1@7e800000 {
> >
> > The node name should be csi@7e800000, not csi1@7e800000. Now, this will
> > probably cause issues with the firmware that looks for csi1 (and csi0 ?)
> > to hand over control of the Unicam CSI-2 receiver to the kernel. I
> > wonder if this is something that could be handled by a firmware update,
> > to also recognize nodes named "csi" ?
> 
> It already looks for any node starting "csi". If you check the
> downstream DT [1], then the nodes are "csi0: csi@7e800000" and "csi1:
> csi@7e801000".

Oops, indeed. I think I was misled by
https://github.com/raspberrypi/linux/blob/rpi-5.10.y/Documentation/devicetree/bindings/media/bcm2835-unicam.txt
that mentions "csi0" and "csi1".

It's all good then. Jean-Michel, can you update the DT bindings in the
next iteration of the series to correct the DT node naming ?

> There is no actual action required to hand the peripheral over to the
> kernel, it just prevents the firmware from using it and causing
> problems (it masks out the interrupt, and that's checked as part of
> the firmware initialising the peripheral).
> 
> If using imx219 or one of the other sensors supported by the firmware,
> "vcgencmd get_camera" should report that the sensor isn't detected,
> and "sudo vcdbg log msg" should have a line similar to
> "020174.613: camsubs: Ignoring camera 0 as unicam device not available"
> 
>   Dave
> 
> [1] https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/bcm270x.dtsi#L88
> 
> > > +                     compatible = "brcm,bcm2835-unicam";
> > > +                     reg = <0x7e800000 0x800>,
> > > +                           <0x7e802000 0x4>;
> > > +                     interrupts = <GIC_SPI 102 IRQ_TYPE_LEVEL_HIGH>;
> > > +                     clocks = <&clocks BCM2835_CLOCK_CAM0>,
> > > +                              <&firmware_clocks 4>;
> > > +                     clock-names = "lp", "vpu";
> > > +                     power-domains = <&power RPI_POWER_DOMAIN_UNICAM0>;
> > > +                     #address-cells = <1>;
> > > +                     #size-cells = <0>;
> > > +                     #clock-cells = <1>;
> >
> > Why do you need #address-cells, #size-cells and #clock-cells ? They're
> > not mentioned in the binding.
> >
> > > +                     status="disabled";
> >
> > Missing spaces around the =.
> >
> > Same comment for the next node.
> >
> > > +             };
> > > +
> > > +             csi1: csi1@7e801000 {
> > > +                     compatible = "brcm,bcm2835-unicam";
> > > +                     reg = <0x7e801000 0x800>,
> > > +                           <0x7e802004 0x4>;
> > > +                     interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
> > > +                     clocks = <&clocks BCM2835_CLOCK_CAM1>,
> > > +                              <&firmware_clocks 4>;
> > > +                     clock-names = "lp", "vpu";
> > > +                     power-domains = <&power RPI_POWER_DOMAIN_UNICAM1>;
> > > +                     #address-cells = <1>;
> > > +                     #size-cells = <0>;
> > > +                     #clock-cells = <1>;
> > > +                     status="disabled";
> > > +             };
> > > +
> > >               pixelvalve3: pixelvalve@7ec12000 {
> > >                       compatible = "brcm,bcm2711-pixelvalve3";
> > >                       reg = <0x7ec12000 0x100>;

-- 
Regards,

Laurent Pinchart

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