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

[Dmitry Baryshkov]

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?

-- 
With best wishes
Dmitry