Subject: Re: [PATCH net-next 14/14] net: stmmac: report PCS configuration changes

From: "Russell King (Oracle)" <[email-masked]>
Date: Mon, 19 Jan 2026 14:27:38 +0000

On Mon, Jan 19, 2026 at 12:34:47PM +0000, Russell King (Oracle) wrote:
> Report if/when qcom-ethqos changes the PCS configuration. With phylink
> now setting the PCS configuration, there should be no need for drivers
> to change this.
> 
> Signed-off-by: Russell King (Oracle) <[email-masked]>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> index f9e7a7ed840b..6a1e30b10740 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> @@ -71,6 +71,7 @@ static inline void dwmac_ctrl_ane(void __iomem *ioaddr, u32 reg, bool ane,
>  				  bool srgmi_ral)
>  {
>  	u32 value = readl(ioaddr + GMAC_AN_CTRL(reg));
> +	u32 old = value, diff;
>  
>  	/* Enable and restart the Auto-Negotiation */
>  	if (ane)
> @@ -84,6 +85,20 @@ static inline void dwmac_ctrl_ane(void __iomem *ioaddr, u32 reg, bool ane,
>  	if (srgmi_ral)
>  		value |= GMAC_AN_CTRL_SGMRAL;
>  
> +	diff = old ^ value;
> +	if (diff & ~GMAC_AN_CTRL_RAN) {
> +		pr_warn("dwmac: PCS configuration changed from phylink by glue, please report: 0x%08x -> 0x%08x\n",
> +			old & ~GMAC_AN_CTRL_RAN, value & ~GMAC_AN_CTRL_RAN);
> +#define REPORT_BIT(x) \
> +		if (diff & GMAC_AN_CTRL_##x) \
> +			pr_warn("dwmac: %8s %u -> %u\n", #x, \
> +				!!(old & GMAC_AN_CTRL_##x), \
> +				!!(value & GMAC_AN_CTRL_##x))
> +		REPORT_BIT(ANE);
> +		REPORT_BIT(SGMRAL);
> +#undef REPORT_BIT

I notice in patchwork, checkpatch doesn't like the "if" starting the in
the macro definition. While that would be true of definitions in kernel
header files which can be used anwhere, for such a simple limited usage
here, wrapping the thing in do { } while(0) is needless baggage, over-
complicates the code, and makes it less readable. So, IMHO, checkpatch
is wrong.

-- 
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