can: m_can: document and add external reset

[PATCH v2 2/2] ARM: dts: stm32: add resets property to m_can nodes in the stm32mp153

Posted by Marc Kleine-Budde 1 month, 4 weeks ago

On the STM32MP153 the m_cam IP cores (a.k.a. FDCAN) have an external
shared reset in the RCC. Add the reset to both m_can nodes.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 arch/arm/boot/dts/st/stm32mp153.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/boot/dts/st/stm32mp153.dtsi b/arch/arm/boot/dts/st/stm32mp153.dtsi
index 4640dafb1598..92794b942ab2 100644
--- a/arch/arm/boot/dts/st/stm32mp153.dtsi
+++ b/arch/arm/boot/dts/st/stm32mp153.dtsi
@@ -40,6 +40,7 @@ m_can1: can@4400e000 {
 		interrupt-names = "int0", "int1";
 		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
 		clock-names = "hclk", "cclk";
+		resets = <&rcc FDCAN_R>;
 		bosch,mram-cfg = <0x0 0 0 32 0 0 2 2>;
 		access-controllers = <&etzpc 62>;
 		status = "disabled";
@@ -54,6 +55,7 @@ m_can2: can@4400f000 {
 		interrupt-names = "int0", "int1";
 		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
 		clock-names = "hclk", "cclk";
+		resets = <&rcc FDCAN_R>;
 		bosch,mram-cfg = <0x1400 0 0 32 0 0 2 2>;
 		access-controllers = <&etzpc 62>;
 		status = "disabled";

-- 
2.47.2

Re: [PATCH v2 2/2] ARM: dts: stm32: add resets property to m_can nodes in the stm32mp153

Posted by Alexandre TORGUE 1 month ago

Hi Marc

On 8/7/25 08:09, Marc Kleine-Budde wrote:
> On the STM32MP153 the m_cam IP cores (a.k.a. FDCAN) have an external
> shared reset in the RCC. Add the reset to both m_can nodes.
> 
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
>   arch/arm/boot/dts/st/stm32mp153.dtsi | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/st/stm32mp153.dtsi b/arch/arm/boot/dts/st/stm32mp153.dtsi
> index 4640dafb1598..92794b942ab2 100644
> --- a/arch/arm/boot/dts/st/stm32mp153.dtsi
> +++ b/arch/arm/boot/dts/st/stm32mp153.dtsi
> @@ -40,6 +40,7 @@ m_can1: can@4400e000 {
>   		interrupt-names = "int0", "int1";
>   		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
>   		clock-names = "hclk", "cclk";
> +		resets = <&rcc FDCAN_R>;
>   		bosch,mram-cfg = <0x0 0 0 32 0 0 2 2>;
>   		access-controllers = <&etzpc 62>;
>   		status = "disabled";
> @@ -54,6 +55,7 @@ m_can2: can@4400f000 {
>   		interrupt-names = "int0", "int1";
>   		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
>   		clock-names = "hclk", "cclk";
> +		resets = <&rcc FDCAN_R>;
>   		bosch,mram-cfg = <0x1400 0 0 32 0 0 2 2>;
>   		access-controllers = <&etzpc 62>;
>   		status = "disabled";
> 

How those reset are handled at driver side ?

regards
alex

Re: [PATCH v2 2/2] ARM: dts: stm32: add resets property to m_can nodes in the stm32mp153

Posted by Marc Kleine-Budde 1 month ago

On 03.09.2025 15:10:42, Alexandre TORGUE wrote:
> Hi Marc
> 
> On 8/7/25 08:09, Marc Kleine-Budde wrote:
> > On the STM32MP153 the m_cam IP cores (a.k.a. FDCAN) have an external
> > shared reset in the RCC. Add the reset to both m_can nodes.
> > 
> > Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> > ---
> >   arch/arm/boot/dts/st/stm32mp153.dtsi | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/st/stm32mp153.dtsi b/arch/arm/boot/dts/st/stm32mp153.dtsi
> > index 4640dafb1598..92794b942ab2 100644
> > --- a/arch/arm/boot/dts/st/stm32mp153.dtsi
> > +++ b/arch/arm/boot/dts/st/stm32mp153.dtsi
> > @@ -40,6 +40,7 @@ m_can1: can@4400e000 {
> >   		interrupt-names = "int0", "int1";
> >   		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
> >   		clock-names = "hclk", "cclk";
> > +		resets = <&rcc FDCAN_R>;
> >   		bosch,mram-cfg = <0x0 0 0 32 0 0 2 2>;
> >   		access-controllers = <&etzpc 62>;
> >   		status = "disabled";
> > @@ -54,6 +55,7 @@ m_can2: can@4400f000 {
> >   		interrupt-names = "int0", "int1";
> >   		clocks = <&rcc CK_HSE>, <&rcc FDCAN_K>;
> >   		clock-names = "hclk", "cclk";
> > +		resets = <&rcc FDCAN_R>;
> >   		bosch,mram-cfg = <0x1400 0 0 32 0 0 2 2>;
> >   		access-controllers = <&etzpc 62>;
> >   		status = "disabled";
> > 
> 
> How those reset are handled at driver side ?

I've created a patch that adds a shared reset to the m_can driver:

| https://lore.kernel.org/all/20250812-m_can-fix-state-handling-v1-7-b739e06c0a3b@pengutronix.de/

The reset is de-asserted during probe and when the interface does up,
otherwise it asserted. This way the IP gets reset only when both
interfaces are down.

regards,
Marc

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