On 01/11/2018 12:55 PM, Andrew Lunn wrote:
> __phy_modify would return the old value of the register before it was
> modified. Thus on success, it does not return 0, but a positive value.
> Thus functions using phy_modify, which is a wrapper around
> __phy_modify, can start returning > 0 on success, rather than 0. As a
> result, breakage has been noticed in various places, where 0 was
> assumed.
>
> Code inspection does not find any current location where the return of
> the old value is currently used.
phy_restore_page() does actually use the old value returned by
__phy_modify(), but treats > 0 and == 0 the same way so it is
technically used, just not as a > 0 quantity it seems.
Russell, are there out of tree call sites (e.g: in your "phy" branch)
that we are going to be breaking if we accept this change?
So have __phy_modify return 0 on
> success. When there is a real need for the old value, either a new
> accessor can be added, or an additional parameter passed.
>
> Fixes: 2b74e5be17d2 ("net: phy: add phy_modify() accessor")
You would probably want to tag it with:
Fixes: fea23fb591cc ("net: phy: convert read-modify-write to phy_modify()")
as well, because that seems to be the problem Niklas and Geert encountered.
> Reported-by: Geert Uytterhoeven <ge...@linux-m68k.org>
> Signed-off-by: Andrew Lunn <and...@lunn.ch>
> ---
>
> Geert, Niklas
>
> Please can you test this and let me know if it fixes the problems you
> see.
>
> drivers/net/phy/phy-core.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index e75989ce8850..36cad6b3b96d 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -336,16 +336,15 @@ EXPORT_SYMBOL(phy_write_mmd);
> */
> int __phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
> {
> - int ret, res;
> + int ret;
>
> ret = __phy_read(phydev, regnum);
> - if (ret >= 0) {
> - res = __phy_write(phydev, regnum, (ret & ~mask) | set);
> - if (res < 0)
> - ret = res;
> - }
> + if (ret < 0)
> + return ret;
>
> - return ret;
> + ret = __phy_write(phydev, regnum, (ret & ~mask) | set);
> +
> + return ret < 0 ? ret: 0;
> }
> EXPORT_SYMBOL_GPL(__phy_modify);
>
>
--
Florian
