Re: [PATCH v4 3/5] memory: tegra186-emc: Support non-bpmp icc scaling

Jon Hunter
2025-12-10T04:08:53Z

On 09/12/2025 05:53, Krzysztof Kozlowski wrote:
> On 09/12/2025 05:26, Aaron Kling wrote:
>> On Sat, Nov 22, 2025 at 6:01 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>
>>> On 21/11/2025 12:21, Jon Hunter wrote:
>>>>
>>>> On 12/11/2025 07:21, Aaron Kling wrote:
>>>>> On Wed, Nov 12, 2025 at 12:18 AM Jon Hunter <jonathanh@nvidia.com> wrote:
>>>>>>
>>>>>>
>>>>>> On 11/11/2025 23:17, Aaron Kling wrote:
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>> Alright, I think I've got the picture of what's going on now. The
>>>>>>> standard arm64 defconfig enables the t194 pcie driver as a module. And
>>>>>>> my simple busybox ramdisk that I use for mainline regression testing
>>>>>>> isn't loading any modules. If I set the pcie driver to built-in, I
>>>>>>> replicate the issue. And I don't see the issue on my normal use case,
>>>>>>> because I have the dt changes as well.
>>>>>>>
>>>>>>> So it appears that the pcie driver submits icc bandwidth. And without
>>>>>>> cpufreq submitting bandwidth as well, the emc driver gets a very low
>>>>>>> number and thus sets a very low emc freq. The question becomes... what
>>>>>>> to do about it? If the related dt changes were submitted to
>>>>>>> linux-next, everything should fall into place. And I'm not sure where
>>>>>>> this falls on the severity scale since it doesn't full out break boot
>>>>>>> or prevent operation.
>>>>>>
>>>>>> Where are the related DT changes? If we can get these into -next and
>>>>>> lined up to be merged for v6.19, then that is fine. However, we should
>>>>>> not merge this for v6.19 without the DT changes.
>>>>>
>>>>> The dt changes are here [0].
>>>>
>>>> To confirm, applying the DT changes do not fix this for me. Thierry is
>>>> having a look at this to see if there is a way to fix this.
>>>>
>>>> BTW, I have also noticed that Thierry's memory frequency test [0] is
>>>> also failing on Tegra186. The test simply tries to set the frequency via
>>>> the sysfs and this is now failing. I am seeing ..
>>
>> With this patch dropped from -next, what needs to happen to get it
>> requeued? I gave an analysis over two weeks ago and have seen no
>> response since.
>
> Hm, I did not see the root cause identified, so maybe I missed something.
>
> Anyway, I am waiting for the patchset to be retested and resent. And
> testing MUST include kernel development process rules, including how
> patches are taken - see maintainer soc profile. Any dependencies must be
> clearly marked.

Yes me too. I am happy to re-test any updates.

Jon

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nvpublic