Kernel 6.7+ broke under-powering of my RX 6700XT. (Archlinux, mesa/amdgpu)

[Romano]

Hello everyone,

patch by user @fililip was posted there, but not submitted:

"I think I'd have to submit it to the linux kernel mailing list, which I 
am kinda scared of 😅. It could be better to submit that patch to Arch 
Linux maintainers; they could include it in their kernel builds."

Implementation of this patch can be simplified by simply setting:

smu->min_power_limit = amdgpu_ignore_min_pcap ? 0 : whatever_default_smuxx;

and then leave rest of the code unchanged(except defining 
amdgpu_ignore_min_pcap variable of course). Nothing tricky nor need to 
revert anything should be needed I hope. Please add it to the general 
kernel as an option, it certainly should not be related to Archlinux only.

Roman



On 2/19/24 12:15, Linux regression tracking (Thorsten Leemhuis) wrote:
> On 17.02.24 14:30, Greg KH wrote:
>> On Sat, Feb 17, 2024 at 02:01:54PM +0100, Roman Benes wrote:
>>> Minimum power limit on latest(6.7+) kernels is 190W for my GPU (RX 6700XT,
>>> mesa, archlinux) and I cannot get power cap as low as before(to 115W),
>>> neither with Corectrl, LACT or TuxClocker and /sys have a variable read-only
>>> even for root. This is not of above apps issue but of the kernel, I read
>>> similar issues from other bug reports of above apps. I downgraded to v6.6.10
>>> kernel and my 115W(under power)cap work again as before.
>> Any chance you can use 'git bisect' to figure out the offending change?
> For the record and everyone that lands here: the cause is known now
> (it's 1958946858a62b ("drm/amd/pm: Support for getting power1_cap_min
> value") [v6.7-rc1]) and the issue afaics tracked here:
>
> https://gitlab.freedesktop.org/drm/amd/-/issues/3183
>
> Other mentions:
> https://gitlab.freedesktop.org/drm/amd/-/issues/3137
> https://gitlab.freedesktop.org/drm/amd/-/issues/2992
>
> Haven't seen any statement from the amdgpu developers (now CCed) yet on
> this there (but might have missed something!). From what I can see I
> assume this will likely be somewhat tricky to handle, as a revert
> overall might be a bad idea here. We'll see I guess.
>
> Roman posted something that apparently was meant to go to the list, so
> let me put it here:
>
> """
> UPDATE: User fililip already posted patch, but it need to be merged,
> discussion is on gitlab link below.
>
> (PS: I hope I am replying correctly to "all" now? - using original addr.)
>
>
>> it seems that commit was already found(see user's 'fililip' comment):
>>
>> https://gitlab.freedesktop.org/drm/amd/-/issues/3183
>> commit 1958946858a62b6b5392ed075aa219d199bcae39
>> Author: Ma Jun <Jun.Ma2 at amd.com>
>> Date:   Thu Oct 12 09:33:45 2023 +0800
>>
>>      drm/amd/pm: Support for getting power1_cap_min value
>>
>>      Support for getting power1_cap_min value on smu13 and smu11.
>>      For other Asics, we still use 0 as the default value.
>>
>>      Signed-off-by: Ma Jun <Jun.Ma2 at amd.com>
>>      Reviewed-by: Kenneth Feng <kenneth.feng at amd.com>
>>      Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>>
>> However, this is not good as it remove under-powering range too far. I
> was getting only about 7% less performance but 90W(!) less consumption
> when set to my 115W before. Also I wonder if we as a OS of options and
> freedom have to stick to such very high reference for min values without
> ability to override them through some sys ctrls. Commit was done by amd
> guy and I wonder if because of maybe this post that I made few months
> ago(business strategy?):
>>
> https://www.reddit.com/r/Amd/comments/183gye7/rx_6700xt_from_230w_to_capped_115w_at_only_10/
>> This is not a dangerous OC upwards where I can understand desire to
> protect HW, it is downward, having min cap at 190W when card pull on
> 115W almost same speed is IMO crazy to deny. We don't talk about default
> or reference values here either, just a move to lower the range of
> options for whatever reason.
>> I don't know how much power you guys have over them, but please
> consider either reverting this change, or give us an option to set
> min_cap through say /sys (right now param is readonly, even for root).
>>
>> Thank you in advance for looking into this, with regards:  Romano
> """
>
> And while at it, let me add this issue to the tracking as well
>
> [TLDR: I'm adding this report to the list of tracked Linux kernel
> regressions; the text you find below is based on a few templates
> paragraphs you might have encountered already in similar form.
> See link in footer if these mails annoy you.]
>
> Thanks for the report. To be sure the issue doesn't fall through the
> cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
> tracking bot:
>
> #regzbot introduced 1958946858a62b /
> #regzbot title drm: amdgpu: under-powering broke
>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
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