[Letux-kernel] jz4780 CI20 v5.8 - SMP

H. Nikolaus Schaller hns at goldelico.com
Sun Jul 5 22:43:50 CEST 2020

Hi Paul,

> Am 05.07.2020 um 19:39 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> Am 05.07.2020 um 19:35 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> Hi Paul,
>>> Am 05.07.2020 um 19:11 schrieb Paul Boddie <paul at boddie.org.uk>:
>>> On Sunday, 5 July 2020 17:41:53 CEST H. Nikolaus Schaller wrote:
>>>>> Am 05.07.2020 um 16:17 schrieb Paul Boddie <paul at boddie.org.uk>:
>>>>> Replying to this again specifically, I found that the DRM/HDMI patches
>>>>> based on letux-5.8-rc3 will not yield a bootable kernel, but by disabling
>>>>> SMP in the configuration it would boot.
>>>> I already had this idea, but haven't tried.
>>>> So the SMP patches are no longer compatible. I have to check if the original
>>>> author has submitted something new or if we can backport something from
>>>> linux-next (if it is there).
>>>> Otherwise we should ask the LKML about the status of merging JZ4780 SMP
>>>> support.
>>> I might have a look at the relevant code, but it would involve some study 
>>> first.
>> I think I have it here:
>> https://git.goldelico.com/?p=letux-kernel.git;a=shortlog;h=refs/heads/letux/jz4780-smp-v6
>> It looks as if I have applied some compile issue fix. But that may be wrong.
>> Other ideas: the hight resolution timer may be broken.
>> There may also be a general MIPS bug wich has been fixed/accepted for mips-fixes:
>> "[PATCH] MIPS: Do not use smp_processor_id() in preemptible code"
> Linus has just merged it some minutes ago:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=45a5ac7a5cc3c71739d240c422c3818a5bc97fc4
> So we will have it in letux-5.8-rc4 tomorrow.

Seems not really be related to jz4780.

But I have found v8 of the jz4780 patches (we have forward-ported v6):


It wasn't simple to apply it to v5.8 but I could
apply it to v5.7 and then rebase.

This needed to move the initialization from prom.c
to setup.c

But here it is:


With this, I could simply do:

git checkout letux-5.8-rc3
git revert letux-base..letux/jz4780-smp-v6
git merge letux/jz4780-smp-v8

It now compiles but I haven't had time to test.
The update to v5.8-rc4 will directly include


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