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SubjectRe: [PATCH v5 0/2] tty: serial: add DT bindings and serial driver for the SiFive FU540 UART
On Thu 18 Apr 2019 at 18:04, Atish Patra <> wrote:

> 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.

I'm trying to get the kernel boot with the current linux kernel DT from
Paul's patch series [0].

Could you point me to some documentation on 2. ?
Or do you know of a way to disable M-mode interrupts from U-boot ?



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

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