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

On Wed, Sep 16, 2026 at 11:01 AM Oleksij Rempel [off-list ref] 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: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij