linux-kernel - Re: [PATCH v5 2/7] dt-bindings: wireless: ieee80211: Add disable-rfkill property

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Message-ID: <9b1b461c-f456-44ed-8c46-3405286fc532@kernel.org>
Date: Mon, 22 Dec 2025 12:04:00 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Hans de Goede <hansg@...nel.org>, Bryan O'Donoghue <bod.linux@...w.ie>,
 jerome.debretagne@...il.com, Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Johannes Berg <johannes@...solutions.net>,
 Lorenzo Bianconi <lorenzo@...nel.org>,
 Maximilian Luz <luzmaximilian@...il.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Jeff Johnson <jjohnson@...nel.org>, Manivannan Sadhasivam <mani@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
 platform-driver-x86@...r.kernel.org, ath12k@...ts.infradead.org,
 Jeff Johnson <jeff.johnson@....qualcomm.com>, Dale Whinham <daleyo@...il.com>
Subject: Re: [PATCH v5 2/7] dt-bindings: wireless: ieee80211: Add
 disable-rfkill property

On 22/12/2025 11:23, Hans de Goede wrote:
> +Cc Mani
> 
> Hi,
> 
> On 20-Dec-25 07:04, Bryan O'Donoghue wrote:
>> On 20/12/2025 00:21, Jérôme de Bretagne via B4 Relay wrote:
>>> From: Jérôme de Bretagne <jerome.debretagne@...il.com>
>>>
>>> For some devices, Wi-Fi is entirely hard blocked by default making
>>> the Wi-Fi radio unusable, except if rfkill is disabled as expected
>>> on those models.
>>>
>>> Commit c6a7c0b09d5f ("wifi: ath12k: Add Support for enabling or
>>> disabling specific features based on ACPI bitflag") added a way to
>>> support features set via ACPI, including the DISABLE_RFKILL bit.
>>>
>>> Add a disable-rfkill property to expose the DISABLE_RFKILL bit
>>> equivalent for devices described by a Devicetree instead of ACPI.
>>>
>>> Signed-off-by: Jérôme de Bretagne <jerome.debretagne@...il.com>
>>> ---
>>>   Documentation/devicetree/bindings/net/wireless/ieee80211.yaml | 6 ++++++
>>>   1 file changed, 6 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/net/wireless/ieee80211.yaml b/Documentation/devicetree/bindings/net/wireless/ieee80211.yaml
>>> index d89f7a3f88a71d45d6f4ab2ae909eae09cbcaf9a..c10a4675640be947cd0b5eaec2c7ff367fd93945 100644
>>> --- a/Documentation/devicetree/bindings/net/wireless/ieee80211.yaml
>>> +++ b/Documentation/devicetree/bindings/net/wireless/ieee80211.yaml
>>> @@ -29,6 +29,12 @@ properties:
>>>         different 5 GHz subbands. Using them incorrectly could not work or
>>>         decrease performance noticeably
>>>
>>> +  disable-rfkill:
>>> +    type: boolean
>>> +    description:
>>> +      Disable rfkill for some devices on which Wi-Fi would be entirely hard
>>> +      blocked by default otherwise
>>> +
>>>   additionalProperties: true
>>>
>>>   examples:
>>>
>>> -- 
>>> 2.47.3
>>>
>>>
>>>
>>
>> Is this really a hardware description though ?
> 
> I would say yes it is. The wifi chip has an rfkill input pin and
> things will be broken when that pin is hardwired to a fixed value
> rather then being actually connected to a GPIO from say
> the embedded controller.

You still do not describe the hardware. Read my comment.

> 
> So I think that we would need here is not a disable-rfkill property
> but some way to indicate in the DT-node that the rfkill input pin
> is not connected and thus should be ignored.
> 
> This (the rfkill input pin being not-connected) IMHO very much
> is hw-description.
> 
> Also see the
> "[PATCH 0/9] Add support for handling PCIe M.2 Key E connectors in devicetree"
> series and then specifically:
> 
> https://lore.kernel.org/platform-driver-x86/20251112-pci-m2-e-v1-7-97413d6bf824@oss.qualcomm.com/
> 
> Which adds:
> 
> +  w_disable1-gpios:
> +    description: GPIO controlled connection to W_DISABLE1# signal. This signal
> +      is used by the system to disable WiFi radio in the M.2 card. Refer, PCI
> +      Express M.2 Specification r4.0, sec 3.1.12.3 for more details.
> +    maxItems: 1
> 
> What if there is no such GPIO, because the W_DISABLE1# signal is hardwired
> in a specific implementation of the M.2 slot ?
> 
> In that case we will also need some way to propagate that info to the wifi
> driver, having some sort of generic devicetree property for wifi-cards
> which can be injected as a software-node property in the PCI-device being
> instantiated for the WIFI card to let the driver no not to honor to
> W_DISABLE1# signal will be useful here too and this is as hardware-description
> as hardware-description can get.

Please do not use antipatterns as examples. Above patchset is obviously
wrong there, it's a terrible example but also completely different thing
(spec). This is not a spec here.


Best regards,
Krzysztof