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SubjectRe: [PATCH v5 0/2] tty: serial: add DT bindings and serial driver for the SiFive FU540 UART
On 4/18/19 4:22 PM, Kevin Hilman wrote:
> Hi Paul,
> Paul Walmsley <> writes:
>> This series adds a serial driver, with console support, for the
>> UART IP block present on the SiFive FU540 SoC. The programming
>> model is straightforward, but unique.
>> Boot-tested on a SiFive FU540 HiFive-U board, using BBL and the
>> open-source FSBL (with appropriate patches to the DT data).
>> This fifth version fixes a bug in the set_termios handler,
>> found by Andreas Schwab <>.
>> The patches in this series can also be found, with the PRCI patches,
>> DT patches, and DT prerequisite patch, at:
> I tried this branch, and it doesn't boot on my unleashed board.
> Here's the boot log when I pass the DT built from your branch via
> u-boot:

Unfortunately, that won't work. The current DT modifications by OpenSBI.

1. Change hart status to "masked" from "okay".
2. M-mode interrupt masking in PLIC node.
3. Add a chosen node for serial access in U-Boot.

You can ignore 3 for your use case. However, if you pass a dtb built
from source code, that will have hart0 enabled and M-mode interrupts
enabled in DT.

Not sure if we should do these DT modifications in U-Boot as well.

I also noticed that your kernel is booting only 1 hart.
Just FYI: RISC-V SMP for U-Boot patches are merged in master. So you
should be able to boot all cpus. You can ingore FU540_ENABLED_HART_MASK
in OpenSBI build as well.

> I also tried the same thing, but using the DT that's hard-coded into
> SBI/u-boot. That doesn't boot fully either[1], but one thing I noted is
> that with the DT from the kernel tree, the printk timestamps aren't
> moving. Maybe I'm still missing some kconfig options to enable the
> right clock and/or IRQ controllers? I'm using this fragment[2] on top of
> the default defconfig (arch/riscv/configs/defconfig).
> Could you share the defconfig you're using when testing your branch?
> Also for reference, I'm able to successfully build/boot the
> 5.1-rc1-unleashed branch from Atish's tree[3] using that kconfig
> fragment[2] (and the hard-coded DT from u-boot/SBI). Full log here[4].
> Thanks,
> Kevin
> [1]
> [2]
> [3]
> [4]
> _______________________________________________
> linux-riscv mailing list

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