netdev - Re: [PATCH net-next v2 3/6] net: dsa: lantiq: allow arbitrary MII registers

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Message-ID: <aWhFohyjEnaIeHSS@makrotopia.org>
Date: Thu, 15 Jan 2026 01:40:50 +0000
From: Daniel Golle <daniel@...rotopia.org>
To: Hauke Mehrtens <hauke@...ke-m.de>, Andrew Lunn <andrew@...n.ch>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Chen Minqiang <ptpt52@...il.com>, Xinfa Deng <xinfa.deng@...inet.com>
Subject: Re: [PATCH net-next v2 3/6] net: dsa: lantiq: allow arbitrary MII
 registers

On Thu, Jan 15, 2026 at 12:57:07AM +0000, Daniel Golle wrote:
> The Lantiq GSWIP and MaxLinear GSW1xx drivers are currently relying on a
> hard-coded mapping of MII ports to their respective MII_CFG and MII_PCDU
> registers and only allow applying an offset to the port index.
> 
> While this is sufficient for the currently supported hardware, the very
> similar Intel GSW150 (aka. Lantiq PEB7084) cannot be described using
> this arrangement.
> 
> Introduce two arrays to specify the MII_CFG and MII_PCDU registers for
> each port, replacing the current bitmap used to safeguard MII ports as
> well as the port index offset.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
> v2:
>  * introduce GSWIP_MAX_PORTS macro
> 
>  drivers/net/dsa/lantiq/lantiq_gswip.c        | 30 ++++++++++++++++----
>  drivers/net/dsa/lantiq/lantiq_gswip.h        |  6 ++--
>  drivers/net/dsa/lantiq/lantiq_gswip_common.c | 27 +++---------------
>  drivers/net/dsa/lantiq/mxl-gsw1xx.c          | 30 ++++++++++++++++----
>  4 files changed, 56 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/net/dsa/lantiq/lantiq_gswip.c b/drivers/net/dsa/lantiq/lantiq_gswip.c
> index b094001a7c805..4a1be6a1df6fe 100644
> --- a/drivers/net/dsa/lantiq/lantiq_gswip.c
> +++ b/drivers/net/dsa/lantiq/lantiq_gswip.c
> @@ -463,10 +463,20 @@ static void gswip_shutdown(struct platform_device *pdev)
>  }
>  
>  static const struct gswip_hw_info gswip_xrx200 = {
> -	.max_ports = 7,
> +	.max_ports = GSWIP_MAX_PORTS,
>  	.allowed_cpu_ports = BIT(6),
> -	.mii_ports = BIT(0) | BIT(1) | BIT(5),
> -	.mii_port_reg_offset = 0,
> +	.mii_cfg = {
> +		[0 ... GSWIP_MAX_PORTS - 1] = -1,
> +		[0] = GSWIP_MII_CFGp(0),
> +		[1] = GSWIP_MII_CFGp(1),
> +		[5] = GSWIP_MII_CFGp(5),
> +	},

Kernel CI trips with
warning: initialized field overwritten [-Woverride-init]

Would it be ok to enclose the gswip_hw_info initializers with
__diag_push();
__diag_ignore_all("-Woverride-init",
		  "logic to initialize all and then override some is OK");

like it is done in drivers/net/ethernet/renesas/sh_eth.c?

Or should I rather keep the .mii_ports bitmap in addition to the array
to indicate the indexes with valid values?