garbled screen with RPI4 on 5.10-rc2

[Maxime Ripard]

On Tue, Nov 03, 2020 at 12:59:43PM +0100, Lucas Nussbaum wrote:
> Salut Maxime,
> 
> On 03/11/20 at 12:32 +0100, Maxime Ripard wrote:
> > On Mon, Nov 02, 2020 at 11:19:57PM +0100, Lucas Nussbaum wrote:
> > > Hi,
> > > 
> > > I'm getting a half-garbled screen with an RPI4 on linux 5.10-rc2 (which
> > > includes Maxime Ripard's changes to the VC4 DRM driver).
> > > 
> > > Photo: https://blop.info/pub/rpi4-vc4.jpg
> > > 
> > > dmesg output: https://blop.info/pub/dmesg.txt
> > > 
> > > Including:
> > > [    0.000000] Kernel command line: video=HDMI-A-1:1920x1080M at 60,margin_left=48,margin_right=48,margin_top=48,margin_bottom=48 dma.dmachans=0x71f5 bcm2709.boardrev=0xd03114 bcm2709.serial=0x99e79233 bcm2709.uart_clock=48000000 bcm2709.disk_led_gpio=42 bcm2709.disk_led_active_low=0 smsc95xx.macaddr=DC:A6:32:BE:A2:01 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=tty0 console=ttyS1,115200 root=/dev/mmcblk1p2 rw elevator=deadline fsck.repair=yes net.ifnames=0  rootwai
> > > 
> > > This is with a Debian image from https://raspi.debian.net/, where I just
> > > upgraded the kernel. I also tried updating *.{dat,elf,bin} from
> > > https://github.com/raspberrypi/firmware/tree/master/boot, but it did not
> > > help.
> > > 
> > > Any ideas?
> > 
> > It's weird. It's on a 1080p display, right? Anything special about it?
> 
> No, the display's normal resolution is 2560x1440.
> 
> xrandr (on my laptop, connected to that screen) says:
> HDMI-1 connected primary 2560x1440+1920+0 (normal left inverted right x axis y axis) 597mm x 336mm
>    2560x1440     59.95*+

Do you have wifi enabled by any chance?

There's some crosstalk between the HDMI signals and the 2.4GHz WiFi, so
it might be the issue. Trying to change the resolution would be a good
test, and if it goes away with a lower resolution, could you try that
series?

https://patchwork.kernel.org/project/dri-devel/list/?series=373805

> > Can you share your config.txt too?
> 
> $ cat /boot/firmware/config.txt
> arm_64bit=1
> enable_uart=1
> upstream_kernel=1
> kernel=vmlinuz-5.10.0-rc2
> initramfs initrd.img-5.10.0-rc2
> 
> Should I try to force the video= parameter according to
> https://www.raspberrypi.org/documentation/configuration/config-txt/video.md ?

It might be a 64-bit related issue too though, I haven't tested a 64bit
kernel for a while.

Maxime
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