Re: [PATCH v1] arm64: dts: qcom: Enable CAN RX via GPIO expander

[Konrad Dybcio]

On 4/14/26 8:09 PM, Dmitry Baryshkov wrote:
> On Tue, Apr 14, 2026 at 06:20:14PM +0200, Konrad Dybcio wrote:
>> On 4/14/26 6:08 PM, Dmitry Baryshkov wrote:
>>> On Thu, Apr 02, 2026 at 04:22:53PM +0530, Anup Kulkarni wrote:
>>>> Few CAN controllers, part of RTSS sub-system on LeMans, route
>>>> their RX signal through a I2C GPIO expander at address 0x3b.
>>>> RTSS subsystem is an MCU like sub-system on LeMans with independent
>>>> booting capability through OSPI interface and supports peripherals like
>>>> RGMII, CAN-FD, UART, I2C, SPI etc.
>>>>
>>>> Describe this hardware wiring by configuring the expander GPIO 4 pin as
>>>> hog with output-high, asserting the selected line during boot.
>>>
>>> Missing platform name in the subject.
>>>
>>>>
>>>> Signed-off-by: Anup Kulkarni <anup.kulkarni@xxxxxxxxxxxxxxxx>
>>>> ---
>>>>  arch/arm64/boot/dts/qcom/lemans-evk.dts | 7 +++++++
>>>>  1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/lemans-evk.dts b/arch/arm64/boot/dts/qcom/lemans-evk.dts
>>>> index a1ef4eba2a20..b8371bdf9933 100644
>>>> --- a/arch/arm64/boot/dts/qcom/lemans-evk.dts
>>>> +++ b/arch/arm64/boot/dts/qcom/lemans-evk.dts
>>>> @@ -615,6 +615,13 @@ expander3: gpio@3b {
>>>>  		interrupts-extended = <&tlmm 39 IRQ_TYPE_LEVEL_LOW>;
>>>>  		pinctrl-0 = <&expander3_int>;
>>>>  		pinctrl-names = "default";
>>>> +
>>>> +		rtss-can-sel-hog {
>>>
>>> Why is it being described as a hog rather than a pinctrl used by the
>>> CAN device?
>>
>> My understanding is that the CAN bus is managed by SAIL ("RTSS")
> 
> So, Linux can affect what is being required for the safety island?

Seems that way!

Konrad