Re: Raspberry Pi 4 support on 32 bit earmv7hf GENERIC kernel

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

> tsutsui%ceres.dti.ne.jp@localhost (Izumi Tsutsui) writes:
> 
> >> >I'm not familiar FDT or Raspberry Pi firmware, but ofctl says:
> >> 
> >> Yes. It has been deleted in "our" dtb file.
> 
> >Sorry, I don't see your point.  What's your actual suggestion?
> >To revert some NetBSD's change in dts files??
> 
> 
> My point is that with a suitable fdt, you already have support
> for the framebuffer. That's the easiest way and works since
> many years.
> 
> % ofctl -p /soc/fb
> [Caching 235 nodes and 1235 properties]
> compatible              6272636d 2c62636d 32383335 2d666200   "brcm,bcm2835-fb"
> name                    666200.. ........ ........ ........   "fb"
> phandle                 0000008f ........ ........ ........   ....
> status                  6f6b00.. ........ ........ ........   ok.
> 
> genfb0 at simplebus1: switching to framebuffer console

I think there may still be two different framebuffer paths mixed
together here.

I understand the point about /soc/fb and brcm,bcm2835-fb, but
when I look at the current DTS files in src/sys/external/gpl2/dts,
"brcm,bcm2835-fb" comes only from bcm2835-common.dtsi:

---
% grep bcm2835-fb *
bcm2835-common.dtsi:                    compatible = "brcm,bcm2835-fb";
mirage-% grep bcm2835-common.dtsi *
bcm2835.dtsi:#include "bcm2835-common.dtsi"
bcm2836.dtsi:#include "bcm2835-common.dtsi"
bcm2837.dtsi:#include "bcm2835-common.dtsi"
mirage-% egrep  'bcm283[567]\.dtsi' *
bcm2835-rpi-a-plus.dts:#include "bcm2835.dtsi"
bcm2835-rpi-a.dts:#include "bcm2835.dtsi"
bcm2835-rpi-b-plus.dts:#include "bcm2835.dtsi"
bcm2835-rpi-b-rev2.dts:#include "bcm2835.dtsi"
bcm2835-rpi-b.dts:#include "bcm2835.dtsi"
bcm2835-rpi-cm1.dtsi:#include "bcm2835.dtsi"
bcm2835-rpi-zero-w.dts:#include "bcm2835.dtsi"
bcm2835-rpi-zero.dts:#include "bcm2835.dtsi"
bcm2836-rpi-2-b.dts:#include "bcm2836.dtsi"
bcm2837-rpi-3-a-plus.dts:#include "bcm2837.dtsi"
bcm2837-rpi-3-b-plus.dts:#include "bcm2837.dtsi"
bcm2837-rpi-3-b.dts:#include "bcm2837.dtsi"
bcm2837-rpi-cm3.dtsi:#include "bcm2837.dtsi"
bcm2837-rpi-zero-2-w.dts:#include "bcm2837.dtsi"
bcm283x.dtsi: * bcm2835.dtsi and bcm2836.dtsi.
%
---

For Raspberry Pi 4 (with BCM2711):

- bcm2711-rpi-4-b.dts includes bcm2711.dtsi
- bcm2711-rpi-400.dts includes bcm2711-rpi-4-b.dts
- bcm2711-rpi-cm4.dtsi includes bcm2711.dtsi
- bcm2711-rpi-cm4-io.dts includes bcm2711-rpi-cm4.dtsi

I do not see any "brcm,bcm2835-fb" node in that bcm2711 DTS paths.

There is no override .dts file for rpi-4/bcm2711 variants in
src/sys/arch/arm/dts/ either:
 https://nxr.netbsd.org/xref/src/sys/arch/arm/dts/


So, at least from what I can see in the current tree,
this still looks like a separate /chosen/simple-framebuffer
enumeration issue on RPi4.  What I am tryingto handle in this
thread is this simple-framebuffer case.

As noted in my past post, Raspberry Pi 4 firmware (start4.elf)
populates /chosen dynamically, places "simple-framebuffer" under it,
and also gives "/chosen" node the non-standard compatible string
"simple_bus".

Currently fdt_match() in src/sys/dev/fdt/fdtbus.c matches
compatible "simple-bus" or "/chosen node without a compatible property"
so "/chosen" with compatible string "simple_bus" in this rpi-4 case
is not attached as simplebus.

That is why the patch below only extends the existing /chosen
special case to cover /chosen with compatible "simple_bus".

 https://github.com/NetBSD/src/commit/8d680e0d7b993a09afb7234286cf48554f824e24

---
diff --git a/sys/dev/fdt/fdtbus.c b/sys/dev/fdt/fdtbus.c
index e557b0c6479a..828b673353a8 100644
--- a/sys/dev/fdt/fdtbus.c
+++ b/sys/dev/fdt/fdtbus.c
@@ -93,6 +93,11 @@ static const struct device_compatible_entry compat_data[] = {
 	DEVICE_COMPAT_EOL
 };
 
+static const struct device_compatible_entry chosen_compat_data[] = {
+	{ .compat = "simple_bus" },
+	DEVICE_COMPAT_EOL
+};
+
 CFATTACH_DECL2_NEW(simplebus, sizeof(struct fdt_softc),
     fdt_match, fdt_attach, NULL, NULL, fdt_rescan, fdt_childdet);
 
@@ -116,6 +121,15 @@ fdt_match(device_t parent, cfdata_t cf, void *aux)
 			return 1;
 	}
 
+	/*
+	 * Raspberry Pi 4 firmware (start4.elf) may populate /chosen node
+	 * dynamically and set a non-standard compatible string "simple_bus".
+	 * Treat that case like the existing /chosen special case above.
+	 */
+	if (OF_finddevice("/chosen") == phandle &&
+	    of_compatible_match(phandle, chosen_compat_data))
+		return 1;
+
 	/* Always match the root node */
 	return OF_finddevice("/") == phandle;
 }

---

If there is another bcm2711-side framebuffer path I should be
looking at instead, I would appreciate a pointer. Otherwise,
unless there are objections, I am inclined to proceed with
this narrow /chosen-specific workaround.

Thanks,
---
Izumi Tsutsui