Status of Raspberry Pi 4 in Mainline

[swahren]

For those how are interested, Nicolas Saenz Julienne and i working on Mainline support for the Raspberry Pi 4. The plan was to introduce initial Raspberry Pi 4 support (only debug UART, no fancy stuff like GENET, V3D, USB 3.0 or arm64) for Linux 5.4. Unfortunately there were a lot of issues (especially DMA stuff) which delayed everything to the next release. At least the pinctrl and the mmc stuff has been merged and the clock will follow soon.

Here is the issue to keep track on this:
https://github.com/lategoodbye/rpi-zero/issues/43

[swahren]

Today the relevant I2C changes has been applied to for-next:
https://marc.info/?l=linux-i2c&m=156692552019278

[swahren]

Today i applied the initial Raspberry Pi 4 device tree:
https://marc.info/?l=linux-arm-kernel&m ... 825574&w=2

[swahren]

This week the GENET support has been applied to net-next:
https://lore.kernel.org/netdev/15735017 ... t@gmx.net/

[Gavinmc42]

I would have thought arm64 is the preferred mainline kernel.
Optimizing for Aarch64 would give a better future and minimize the support required.

[swahren]

I would have thought arm64 is the preferred mainline kernel.
Optimizing for Aarch64 would give a better future and minimize the support required.

From kernel perspective there is no preference. Both must work, but the BCM2711 / PCIe stuff needs some extra work for arm64. Nicolas Saenz Julienne takes care of this and hopefully in Linux 5.5 there will be basic arm64 support.

[swahren]

Linux 5.5 is almost ready, so a short update for the upcoming features in Mainline Linux 5.6:
- hwrng: iproc-rng200 - Add support for BCM2711
- thermal: Add BCM2711 thermal driver
- PCI: brcmstb: Add Broadcom STB PCIe host controller driver

[Gavinmc42]

Nice, thanks for the update.
So it is looking like 5.6 will be the cross over point for Pi4 on mainstream?
Anything missing?

[swahren]

Nice, thanks for the update.
So it is looking like 5.6 will be the cross over point for Pi4 on mainstream?
Anything missing?

The whole graphics stuff (VC4, V3D), DMA engine and VCHIQ. I think they are more time consuming.

[Gavinmc42]

The whole graphics stuff (VC4, V3D), DMA engine and VCHIQ. I think they are more time consuming.

Have you seen the new v3d stuff in mesa 19.3.0?
Compute Shaders yippee, er how do I use them

Yep camera, mmal stuff is not the job for mere mortals, need wizards for that.

[swahren]

Here are the upcoming features for Mainline Linux 5.7:
- 1920x1200@60Hz support for VC4 KMS of BCM283x
- power saving (LPM) support for VIA LABS VL805
- extend pinctrl/gpio driver to support all 58 GPIOs of BCM2711
- add GPIO labels for Raspberry Pi 4 board
- driver for Sony IMX219 sensor
- bcm2835aux-uart: Support RS485 software emulation

Additionally some patches for BCM2711 VC4 KMS and SD power (required for recent RPi 4 boards) has been merged, but are not functional.

[cjan]

Here are the upcoming features for Mainline Linux 5.7:
- F2FS Zstd compression support.

[pihacker]

How can I try mainline linux kernel for rapsberry pi 4? Is there any instructions to compile mainline kernel? I've tried to compile it using this instructions - https://www.raspberrypi.org/documentati ... uilding.md, but my raspberry struck at loading with rainbow screen and noting on serial console. I tried to use default bootloader, not u-boot.

[swahren]

How can I try mainline linux kernel for rapsberry pi 4? Is there any instructions to compile mainline kernel? I've tried to compile it using this instructions - https://www.raspberrypi.org/documentati ... uilding.md, but my raspberry struck at loading with rainbow screen and noting on serial console. I tried to use default bootloader, not u-boot.

I hope this Gist may help you a little bit: https://gist.github.com/lategoodbye/c73 ... aed8c68f75

[Gavinmc42]

extend pinctrl/gpio driver to support all 58 GPIOs of BCM2711

Compute modules coming? That would be handy

[swahren]

Anyone who wants to test KMS for the RPi 4 could use Maxime Ripard's working branch:
https://git.kernel.org/pub/scm/linux/ke ... h=rpi4-kms

[pihacker]

I hope this Gist may help you a little bit: https://gist.github.com/lategoodbye/c73 ... aed8c68f75

Thank you a lot! I finally managed to compile and boot from mainline kernel!

I also faced a couple of issues:

• RPI4 cannot startup from mmcblk0p2 since name of a block device is changed somehow to mmcblk1p2, it just throw me into rootfs emergency shell, so I needed to change cmdline.txt a bit
• During boot, RPI stucks at systemd job "A start job is running for /dev/mmcblk0p1", so wrong block device name appears here again and I don't know where it comes from. Does it relate to initramfs in /boot? Since I didn't change it for one produced with kernel building.
• Ethernet doesn't work. Should I add some config options before kernel building?

Could you please suggest me ways to solve this issues?

[PhilE]

As I understand, "upstream" are wanting to discourage people from using device names to identify partitions, preferring volume labels and UUIDs instead. That is why there is no way to force a particular mmcblk index (e.g. mmcblk0) to be used on a specific MMC interface. In the downstream rpi-* trees we include a patch that sets the index based on aliases found in the DTB. Try using a PARTUUID or PARTLABEL instead.

It's not clear what would be expecting there to be a Bluetooth device on one of the MMC/SDIO interfaces. The upstream .dts file declares a Bluetooth interface ("brcm,bcm43438", interestingly) on UART0.

[pihacker]

It's not clear what would be expecting there to be a Bluetooth device on one of the MMC/SDIO interfaces. The upstream .dts file declares a Bluetooth interface ("brcm,bcm43438", interestingly) on UART0.

I'm sorry for a wrong error message, I've fixed my previous post. It actually was two unrelated messages -- one about bluetooth and second about mmcblk0p1, and rpi stuck for a 90 second during boot at that message.
The bigger problem is actually ethernet, I've looked into dmesg and found two messages:
could not attach to PHY
bcmgenet fd580000.ethernet eth0: failed to connect to PHY

What could that mean?

[PhilE]

What is the value of the phy-mode property in your bcm2711-rpi-4-b.dts? If it's "rgmii-rxid" then try changing it to "rgmii", and vice versa.

[pihacker]

What is the value of the phy-mode property in your bcm2711-rpi-4-b.dts? If it's "rgmii-rxid" then try changing it to "rgmii", and vice versa.

I tried both with no success. I think I'm missing some .config parameters before compilation.

[PhilE]

I'm sure @swahren will be able to help with that.

[pihacker]

@PhilE thanks. It's even more strange because wifi works! But still missing ethernet

UPD: One more thing to notice is that I use almost empty config.txt. Maybe I should add some options to make eth working with mainline kernel?
UPD2: It seems that GPIO doesn't work too, because serial console doesn't show anything to me.

[swahren]

At first the intention of this thread wasn't to solve mainline kernel issues. This should be separate threads.

@pihacker You never mentioned the kernel version or the base of your kernel config you are using.

Did you overwrite the bcm2711-rpi-4-b.dtb on your sd card with the mainline version?
For ethernet you should use multi_v7_defconfig and make sure CONFIG_BROADCOM_PHY=y
For USB you also need to enable CONFIG_ARM_LPAE and CONFIG_PCIE_BRCMSTB.
In order to get a serial console, please replace serial0 with ttyS1 in the cmdline.txt.

Edit: For experiments with the mainline kernel, i strongly recommend to use Raspbian / Raspberry Pi OS as rootfs.

[pihacker]

@swahren moved discussion to a new thread -- viewtopic.php?f=71&t=276236