linux-kernel - Re: [PATCH 2/2] dt-bindings: wireless: ath: Deprecate 'qcom,calibration-variant' property

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Message-ID: <fmumja63j3xvbvfxlmtnkfubgw4jwo5f43srrpfgqrxyqknrj4@izsqazgbiehp>
Date: Fri, 14 Nov 2025 16:32:15 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Jeff Johnson <jjohnson@...nel.org>,
        Johannes Berg <johannes@...solutions.net>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, ath10k@...ts.infradead.org,
        ath11k@...ts.infradead.org, devicetree@...r.kernel.org,
        ath12k@...ts.infradead.org,
        Miaoqing Pan <miaoqing.pan@....qualcomm.com>
Subject: Re: [PATCH 2/2] dt-bindings: wireless: ath: Deprecate
 'qcom,calibration-variant' property

On Fri, Nov 14, 2025 at 11:47:25AM +0100, Krzysztof Kozlowski wrote:
> On 14/11/2025 11:22, Manivannan Sadhasivam wrote:
> > On devicetree platforms, ath{10k/11k} drivers rely on the presence of the
> > 'qcom,calibration-variant' property to select the correct calibration data
> > for device variants with colliding IDs.
> > 
> > But this property based selection has its own downside that it needs to be
> > added to the devicetree node of the WLAN device, especially for PCI based
> > devices. Currently, the users/vendors are forced to hardcode this property
> > in the PCI device node. If a different device need to be attached to the
> > slot, then the devicetree node also has to be changed. This approach is not
> > scalable and creates a bad user experience.
> > 
> > So deprecate this property from WLAN devicetree nodes and let the drivers
> > do the devicetree model based calibration variant lookup using a static
> > table.
> > 
> > This also warrants removing the property from examples in the binding.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> > ---
> 
> The problem - visible in one of the examples here - is that one board
> has multiple WiFi chips and they use different calibration-variant
> properties. How do you find the right calibration variant for such case
> based on board machine match?
> 

I suspect the legitimacy of the example here. I don't understand how a single
machine can have same devices with 3 different calibration data.

AFAIU, calibration data is specific to the platform design. And I don't see any
upstream supported devicetree having similar properties.

- Mani

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