linux-kernel - Re: [PATCH 0/2] wifi: ath: Use static calibration variant table for devicetree platforms

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Message-ID: <jnggqxqv3rjzhyevovnnxzplfhl3t6auhhvmoz7wxmsf6awgdx@dusdgxwsxvts>
Date: Mon, 17 Nov 2025 14:30:40 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
To: Baochen Qiang <baochen.qiang@....qualcomm.com>
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 0/2] wifi: ath: Use static calibration variant table for
 devicetree platforms

On Mon, Nov 17, 2025 at 10:36:39AM +0800, Baochen Qiang wrote:
> 
> 
> On 11/14/2025 6:22 PM, Manivannan Sadhasivam wrote:
> > Hi,
> > 
> > This series aims to deprecate the usage of "qcom,*calibration-variant"
> > devicetree property to select the calibration variant for the WLAN devices. This
> > is necessary for WLAN devices connected using PCI bus, as hardcoding the device
> > specific information in PCI devicetree node causes the node to be updated every
> > time when a new device variant is attached to the PCI slot. This approach is not
> > scalable and causes bad user experience.
> 
> I am not very clear about the problem here: is calibration variant device/module specific,
> or platform specific? If it is module specific, why the lookup is based on the machine
> 'model' property? While if it is platform specific, why do we need to update devicetree
> node whenever a new device is attached?
> 

I think I mixed the usecase of the 'firmware-name' property in the above
description.

But nevertheless, the calibration info platform specific, and hardcoding the DT
property fixes the location of the WLAN card with a specific slot. For instance,
if the board has a couple of M.2 slots, users should be free to plug the WLAN in
any slot, not just a single slot where the property was defined in DT.

Also, if the users plug-in the WLAN card of another vendor, not Qcom, this
property is irrelevant/wrong.

PCIe slots should be plug and play i.e., users should plug-in any M.2 card and
expect it to work.

However, as I learned from Jeff, calibration variant property is also going to
be required in cases like router boards where each slot is dedicated to a fixed
band and the calibration variant is going to be different for each band for the
platform. So unlike I thought, this DT property cannot be deprecated. But going
forward, I'd like it to be used only in these special usecases. Most of the
upstream DTS have a single calibration variant for the platform and for those
generic usecases, this static table should be used.

- Mani

> > 
> > So to avoid relying on the "qcom,*calibration-variant" property, this series
> > introduces a new static calibration variant table based lookup. The newly
> > introduced helper, ath_get_calib_variant() will parse the model name from
> > devicetree and use it to do the variant lookup during runtime. The
> > ath_calib_variant_table[] will hold all the model and calibration variant
> > entries for the supported devices.
> > 
> > Going forward, new entries will be added to this table to support calibration
> > variants.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> > ---
> > Manivannan Sadhasivam (2):
> >       wifi: ath: Use static calibration variant table for devicetree platforms
> >       dt-bindings: wireless: ath: Deprecate 'qcom,calibration-variant' property
> > 
> >  .../bindings/net/wireless/qcom,ath10k.yaml         |  1 +
> >  .../bindings/net/wireless/qcom,ath11k-pci.yaml     |  3 +-
> >  .../bindings/net/wireless/qcom,ath11k.yaml         |  1 +
> >  .../bindings/net/wireless/qcom,ath12k-wsi.yaml     |  6 +-
> >  .../bindings/net/wireless/qcom,ipq5332-wifi.yaml   |  2 +-
> >  drivers/net/wireless/ath/ath.h                     | 98 ++++++++++++++++++++++
> >  drivers/net/wireless/ath/ath10k/core.c             |  5 ++
> >  drivers/net/wireless/ath/ath11k/core.c             |  7 ++
> >  8 files changed, 115 insertions(+), 8 deletions(-)
> > ---
> > base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> > change-id: 20251114-ath-variant-tbl-22865456a527
> > 
> > Best regards,
> 

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