linux-kernel - Re: [PATCH v2 1/9] dt-bindings: imx6q-pcie: Add ref clock for i.MX95 PCIe

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Message-ID: <acb6f417-d8ad-4b73-9752-d30da34b204a@kernel.org>
Date: Wed, 25 Sep 2024 21:28:25 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Frank Li <Frank.li@....com>
Cc: Richard Zhu <hongxing.zhu@....com>, l.stach@...gutronix.de,
 kwilczynski@...nel.org, bhelgaas@...gle.com, lpieralisi@...nel.org,
 robh+dt@...nel.org, conor+dt@...nel.org, shawnguo@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, festevam@...il.com,
 s.hauer@...gutronix.de, linux-pci@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, kernel@...gutronix.de, imx@...ts.linux.dev
Subject: Re: [PATCH v2 1/9] dt-bindings: imx6q-pcie: Add ref clock for i.MX95
 PCIe

On 25/09/2024 18:46, Frank Li wrote:
> On Wed, Sep 25, 2024 at 09:50:06AM +0200, Krzysztof Kozlowski wrote:
>> On Wed, Sep 25, 2024 at 02:24:29PM +0800, Richard Zhu wrote:
>>> Previous reference clock of i.MX95 is on when system boot to kernel. But
>>> boot firmware change the behavor, it is off when boot. So it needs be turn
>>> on when it is used. Also it needs be turn off/on when suspend and resume.
>>
>> That's an old platform... How come that you changed bootloader just now?
>> Like 7 or 8 years after?
> 
> It is new platform, which just publish in this year. Old platform reference
> clock was controlled in PCI module, so needn't export to DT. So we have
> not realized it when start i.MX95 work.

Indeed, I missed that it is i.MX95, not i.MX6q.

> 
>>
>> For the future: you should document all clock inputs, not only ones
>> needed for given bootloader...
> 
> Understand.

Sorry, in case of early upstreaming it's understandable.

> 
>>
>>>
>>> Add one ref clock for i.MX95 PCIe. Increase clocks' maxItems to 5 and keep
>>> the same restriction with other compatible string.
>>
>> <form letter>
>> Please use scripts/get_maintainers.pl to get a list of necessary people
>> and lists to CC (and consider --no-git-fallback argument). It might
>> happen, that command when run on an older kernel, gives you outdated
>> entries. Therefore please be sure you base your patches on recent Linux
>> kernel.
>>
>> Tools like b4 or scripts/get_maintainer.pl provide you proper list of
>> people, so fix your workflow. Tools might also fail if you work on some
>> ancient tree (don't, instead use mainline) or work on fork of kernel
>> (don't, instead use mainline). Just use b4 and everything should be
>> fine, although remember about  if you added new
>> patches to the patchset.
>> </form letter>
>>
>> and I was wondering why I cannot find this and previous thread in my
>> inbox... So please stop developing on two year old kernels (and before
>> you say "I do not", well, then fix way how you use tools).
>>
>>
>>>
>>> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
>>> ---
>>>  .../bindings/pci/fsl,imx6q-pcie-common.yaml   |  4 +--
>>>  .../bindings/pci/fsl,imx6q-pcie.yaml          | 25 ++++++++++++++++---
>>>  2 files changed, 23 insertions(+), 6 deletions(-)
>>>
>>
>> You missed to update ep binding.
> 
> So far, EP don't need reference clock. PCIe standard require host provide
> 100MHz reference clock to EP side. But EP side can choose use itself's
> clock or reference clock from PCIe bus. Currently i.MX95 only support clock
> from internal PLL when work as EP mode.

But this patch allowed certain existing variants in EP to have 5 clocks.
You missed to update EP binding...

Best regards,
Krzysztof