Re: [PATCH net-next v3 2/3] net: dsa: realtek: rtl8365mb: extract PHY OCP address halves with FIELD_GET

[Andrew Lunn <andrew@lunn.ch>]

On Wed, Sep 16, 2026 at 11:01:01AM +0200, Oleksij Rempel wrote:
> Extract the two OCP address halves with FIELD_GET() before handing them
> to FIELD_PREP() to build the ADDRESS register value.
> 
> rtl8365mb_phy_ocp_prepare() previously fed FIELD_PREP() the raw
> ocp_addr >> 1 and >> 6. FIELD_PREP() masks the value to the field at run
> time, so that was correct for the current callers, which all pass a
> run-time register address.
> 
> FIELD_PREP()'s compile-time width check only fires for a compile-time
> constant value. None reached it here: the address is computed as
> PHYREG_BASE + regnum * 2 from a run-time regnum. The EEE support that
> follows adds callers with constant OCP addresses (0xa5c4 etc.); clang
> folds those into the inlined ocp_prepare(), so the shifted constant now
> reaches the check, overflows the 5-/4-bit field and breaks the build
> (gcc does not fold it here). FIELD_GET() narrows each half to the field
> width first, so the value already fits.
> 
> No functional change.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew