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Subject: Re: Testing the recent RISC-V DT patchsets
To:     Loys Ollivier <lollivier@baylibre.com>,
        Karsten Merker <merker@debian.org>
Cc:     "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>
References: <alpine.DEB.2.21.9999.1904221705170.18377@viisi.sifive.com>
 <alpine.DEB.2.21.9999.1905280105110.20842@viisi.sifive.com>
 <86o93mpqbx.fsf@baylibre.com>
 <20190528153542.jfkkwycyc3vu6hld@excalibur.cnev.de>
 <081611ea-a0d3-b0c9-3e08-8946513f2174@wdc.com> <86woi94lvs.fsf@baylibre.com>
From:   Atish Patra <atish.patra@wdc.com>
Message-ID: <42a6c3bd-484b-138b-b0f1-2d4b91c5b0bb@wdc.com>
Date:   Wed, 29 May 2019 10:09:19 -0700
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On 5/29/19 3:04 AM, Loys Ollivier wrote:
> On Wed 29 May 2019 at 00:50, Atish Patra <atish.patra@wdc.com> wrote:
> 
>> On 5/28/19 8:36 AM, Karsten Merker wrote:
>>> On Tue, May 28, 2019 at 05:10:42PM +0200, Loys Ollivier wrote:
>>>> On Tue 28 May 2019 at 01:32, Paul Walmsley <paul.walmsley@sifive.com> wrote:
>>>>
>>>>> An update for those testing RISC-V patches: here's a new branch of
>>>>> riscv-pk/bbl that doesn't try to read or modify the DT data at all, which
>>>>> should be useful until U-Boot settles down.
>>> [...]
>>>>> Here is an Linux kernel branch with updated DT data that can be booted
>>>>> with the above bootloader:
>>>>>
>>>>>      https://github.com/sifive/riscv-linux/tree/dev/paulw/dts-v5.2-rc1-experimental
>>>>>
>>>>> A sample boot log follows, using a 'defconfig' build from that branch.
>>>>
>>>> Thanks Paul, I can confirm that it works.
>>>>
>>>> Something is still unclear to myself.
>>>> Using FSBL + riscv-pk/bbl the linux kernel + device tree boots.
>>>> Neither FSBL nor riscv-pk/bbl are modifying the DT.
>>>>
>>>> Using FSBL + OpenSBI + U-Boot the same kernel + device tree hangs on
>>>> running /init.
>>>>
>>>> Would you have any pointer on what riscv-pk does that OpenSBI/U-boot doesn't ?
>>>> Or maybe it is the other way around - OpenSBI/U-boot does something that
>>>> extra that should not happen.
>>>
>>> Hello,
>>>
>>> I don't know which version of OpenSBI you are using, but there is
>>> a problem with the combination of kernel 5.2-rc1 and OpenSBI
>>> versions before commit
>>>
>>>     https://github.com/riscv/opensbi/commit/4e2cd478208531c47343290f15b577d40c82649c
>>>
>>> that can result in a hang on executing init, so in case you
>>> should be using an older OpenSBI build that might be the source
>>> of the problem that you are experiencing.
>>>
>>> Regards,
>>> Karsten
>>>
>>
>> I verified the updated DT with upstream kernel for the boot flow OpenSBI
>> + U-Boot + Linux or OpenSBI + Linux.
>>
>> OpenSBI should be compiled for sifive platform with following additional
>> argument
>>
>> FW_PAYLOAD_FDT_PATH=<linux kernel
>> source>/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dtb
>>
>> FYI: It will only work when kernel is given a payload to U-Boot/OpenSBI
>> directly.
>>
> 
> Hum, I am surprised by this statement.

That's because U-Boot also using the new DT. With FW_PAYLOAD_FDT_PATH, 
OpenSBI ignores the DT from FSBL and U-Boot gets the updated DT from 
OpenSBI.


> I was able to verify the latest DT patch serie from Paul with:
> OpenSBI + U-Boot + Linux & DT.
> 
> Following the OpenSBI documentation [0] with U-Boot payload:
> FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot.bin
> 
> I get an U-Boot prompt and then I can just load the linux kernel and
> device tree from the network.
> 

Cool. This approach will also work where DT is loaded separately after 
U-Boot is booted.

> [0]: https://github.com/riscv/opensbi/blob/master/docs/platform/sifive_fu540.md#building-sifive-fu540-platform
> 
>> Network booting is still not working as the clock driver probe doesn't
>> happen because of the updated DT.
>>
>> -- 
>> Regards,
>> Atish
> 


-- 
Regards,
Atish