netdev - Re: [PATCH v9 1/2] dt-bindings: net: wireless: qcom,ath11k: describe the ath11k on QCA6390

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Date: Tue, 11 Jun 2024 22:05:57 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Kalle Valo <kvalo@...nel.org>, "David S . Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jeff Johnson <jjohnson@...nel.org>, linux-wireless@...r.kernel.org, 
	netdev@...r.kernel.org, devicetree@...r.kernel.org, 
	ath11k@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	ath12k@...ts.infradead.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH v9 1/2] dt-bindings: net: wireless: qcom,ath11k: describe
 the ath11k on QCA6390

On Fri, Jun 7, 2024 at 8:40 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> Kalle,
> All of the devices out there need these supplies, but they are sometimes
> provided by generic PCI supply and on-board regulators. Basically your
> PCI adapter is not the same as QCA6390 chip on Snapdragon board.
>
>
> >
> >> Based on the discussions I have heard only Snapdragon systems who
> >> require all this configuration you describe. Of course there can be
> >> other systems but I have not heard about those.
> >>
> >
> > DT is not configuration, it is description of actual hardware. It
> > doesn't matter if Snapdragon systems are the only ones that actually
> > *require* this description to make WLAN/BT functional upstream. The
> > chipset would be the same on any PCIe board, it's just that the host
> > systems wouldn't need to take care with its power sequence. But for a
> > dynamic board like this, you don't need DT.
> >
>
> Correct.
>
> ...
>
> >
> >>> If your detachable board "just works" then it must be wired in a way
> >>> that enables WLAN the moment it's plugged in but this doesn't happen
> >>> over PCI. The chipset has a power input and GPIOs to enable each
> >>> module.
> >>
> >> I don't know how the boards are implemented but it could be so. But from
> >> host system point of view it's just a regular PCI device.
> >>
> >
> > And you don't need DT anyway for this type of devices.
>
> Detechable board, like PCI adapter, derives these supplies from generic
> PCI whatever-3.3v through additional regulators. All these supplies are
> there - on the board.
>
> >
> >>> Also: I doubt you need DT for your detachable board?
> >>
> >> Sure, I don't need DT but that's not my point. My point is why require
> >> these supplies for _all_ devices having PCI id 17cb:1101 (ie. QCA6390)
> >> then clearly there are such devices which don't need it? To me that's
> >> bad design and, if I'm understanding correctly, prevents use of
> >> qcom,ath11k-calibration-variant property. To me having the supplies
> >> optional in DT is more approriate.
> >>
> >
> > We require them because *they are physically there*.
>
> I understand that for all known DT QCA6390 hardware, the supplies should
> be provided thus they should be required. If in the future we have
> different design or we represent some pluggable PCI card, then:
> 1. Probably that PCI card does not need power sequencing, thus no DT
> description,
> 2. If still needs power sequencing, you can always amend bindings and
> un-require the supplies.
>
>
> Best regards,
> Krzysztof
>

Kalle, does the above answer your questions? Are these bindings good to go?

Bart