net: dsa: microchip: Add strap configuration during reset

[PATCH net-next 0/2] net: dsa: microchip: Add strap configuration during reset

Posted by Bastien Curutchet 6 hours ago

Hi all,

This small series aims to allow to configure the KSZ8463 switch at
reset. This configuration is determined by pin states while the chip is
held in reset. Normally, this kind of configuration is handled with
pull-ups/pull-downs. However, in some designs these pull-ups/pull-downs
can be missing (either intentionally to save power or simply by mistake).
In such cases, we need to manually drive the configuration pins during
reset to ensure the switch is set up correctly.

PATCH 0 adds a new property to the bindings that describes the GPIOs to
be set during reset in order to configure the switch properly. Alongside
this new property, a new 'reset' pinctrl state is introduced.

PATCH 1 implements the use of this property in the driver. I only have a
KSZ8463 to test with, so only its configuration is supported.

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
---
Bastien Curutchet (2):
      dt-bindings: net: dsa: microchip: Add strap description
      net: dsa: microchip: configure strap pins during reset

 .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 12 ++++++
 drivers/net/dsa/microchip/ksz_common.c             | 47 ++++++++++++++++++++++
 2 files changed, 59 insertions(+)
---
base-commit: d0b93fbf220b2e7be093ac336eba3433cf3cd6f0
change-id: 20250904-ksz-strap-pins-2d1305441325

Best regards,
-- 
Bastien Curutchet <bastien.curutchet@bootlin.com>

Re: [PATCH net-next 0/2] net: dsa: microchip: Add strap configuration during reset

Posted by Andrew Lunn 5 hours ago

On Wed, Sep 10, 2025 at 04:55:23PM +0200, Bastien Curutchet wrote:
> Hi all,
> 
> This small series aims to allow to configure the KSZ8463 switch at
> reset. This configuration is determined by pin states while the chip is
> held in reset. Normally, this kind of configuration is handled with
> pull-ups/pull-downs. However, in some designs these pull-ups/pull-downs
> can be missing (either intentionally to save power or simply by mistake).
> In such cases, we need to manually drive the configuration pins during
> reset to ensure the switch is set up correctly.
> 
> PATCH 0 adds a new property to the bindings that describes the GPIOs to
> be set during reset in order to configure the switch properly. Alongside
> this new property, a new 'reset' pinctrl state is introduced.
> 
> PATCH 1 implements the use of this property in the driver. I only have a
> KSZ8463 to test with, so only its configuration is supported.

Are you setting switch state which cannot be set via register writes?

	Andrew