Re: [PATCH] arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES)

Hi Mark,

On 04.06.2021 12:01, Mark Rutland wrote:

On Wed, Jun 02, 2021 at 04:09:19PM +0200, Marek Szyprowski wrote:

quoted

On 02.06.2021 15:51, Mark Rutland wrote:

quoted

On Wed, Jun 02, 2021 at 03:25:41PM +0200, Marek Szyprowski wrote:

quoted

On 27.05.2021 14:43, Will Deacon wrote:
This patch landed in todays linux-next as commit 65688d2a05de ("arm64:
cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES)"). It causes an
issue on Raspberry Pi 3b board. System boots to userspace fine, but then
it hangs somewhere during the init scripts after loading the modules. I
didn't manage to track where it hangs yet though.

Ouch!

I have a 3b in a drawer that I might be able to reproduce the issue
with; can you tell me how you're booting that kernel? e.g. which FW and
DT you're using?

I'm booting the kernel with the mainline dtb
(arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dtb) from the u-boot,
which downloads it via TFTP. I don't remember which firmware version is
there, but without raspberry specific tools (which I don't have deployed
there) it is hard to check that now.

Thanks, this was enough info to get started.

For comparison, I have a 3Bv1.2 board.

I grabbed the latest RPI firmware, built myself a v2021.07-rc3
rpi_3_defconfig u-boot, and got a kernel booting (off the SD card rather
than over the network).

For the kernel I'm testing commit 65688d2a05de; defconfig with DRM and
VC4 built-in, since passing modules around is painful in my setup.

quoted

The rootfs is on SD card, the system is some older Debian release.

For comparison, I built myself a buildroot 2021.02.2 filesystem.

So far, booting up an running I'm not seeeing issues (and no complaints
from KASAN or similar), but I don't have a good way to stress the VC4
GPU, so I might not be triggering whatever's going wrong.

quoted

From the log below I see the last message is about X sockets -- is the

lockup happening when the display manager starts?

I've just checked with the latest firmware from 
https://github.com/raspberrypi/firmware (master branch, just copied 
everything to /boot) and the issue is still there.

If you start from arm64/defconfig without modules, please make sure you 
have enabled all RPi drivers, otherwise VC4 DRM won't come up. I've 
managed to reproduce the issue without the modules with the following 
changes to arm64's defconfig:

./scripts/config -e DRM -e DRM_VC4 -e CONFIG_CLK_RASPBERRYPI -e 
CONFIG_SENSORS_RASPBERRYPI_HWMON -e CONFIG_I2C_BCM2835 -e 
CONFIG_ARM_RASPBERRYPI_CPUFREQ

Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


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