Re: [PATCH net] net: dsa: microchip: Fix KSZ8863 reset problem

[Oleksij Rempel <o.rempel@pengutronix.de>]

Hi,

On Fri, Aug 01, 2025 at 05:22:53PM -0700, Tristram.Ha@microchip.com wrote:
> From: Tristram Ha <tristram.ha@microchip.com>
> 
> ksz8873_valid_regs[] was added for register access for KSZ8863/KSZ8873
> switches, but the reset register is not in the list so
> ksz8_reset_switch() does not take any effect.
> 
> ksz_cfg() is updated to display an error so that there will be a future
> check for adding new register access code.
> 
> A side effect of not resetting the switch is the static MAC table is not
> cleared.  Further additions to the table will show write error as there
> are only 8 entries in the table.

Thank you for fixing it!

> Fixes: d0dec3333040 ("net: dsa: microchip: Add register access control for KSZ8873 chip")
> Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
> ---
>  drivers/net/dsa/microchip/ksz8.c       | 7 ++++++-
>  drivers/net/dsa/microchip/ksz_common.c | 1 +
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/microchip/ksz8.c b/drivers/net/dsa/microchip/ksz8.c
> index 76e490070e9c..6d282a8e3684 100644
> --- a/drivers/net/dsa/microchip/ksz8.c
> +++ b/drivers/net/dsa/microchip/ksz8.c
> @@ -36,7 +36,12 @@
>  
>  static void ksz_cfg(struct ksz_device *dev, u32 addr, u8 bits, bool set)
>  {
> -	regmap_update_bits(ksz_regmap_8(dev), addr, bits, set ? bits : 0);
> +	int ret;
> +
> +	ret = regmap_update_bits(ksz_regmap_8(dev), addr, bits, set ? bits : 0);
> +	if (ret)
> +		dev_err(dev->dev, "can't update reg 0x%x: %pe\n", addr,
> +			ERR_PTR(ret));

Better using ksz_rmw8() instead. It is already providing error message.

In this file there is 4 direct accesses to regmap_update_bits() without
error handling. It would be great if you have chance to replace it with
ksz_rmw8() too.

>  }
>  
>  static void ksz_port_cfg(struct ksz_device *dev, int port, int offset, u8 bits,
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 7292bfe2f7ca..4cb14288ff0f 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -1447,6 +1447,7 @@ static const struct regmap_range ksz8873_valid_regs[] = {
>  	regmap_reg_range(0x3f, 0x3f),
>  
>  	/* advanced control registers */
> +	regmap_reg_range(0x43, 0x43),

This register is no documented in the public documentation. Out of
curiosity, are there some where more information about this two
"reserved" register ranges: 0x3A-0x3E and 0x40-0x5F?

Best regards,
Oleksij
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