netdev - Re: Issue with commit fea23fb591cc "net: phy: convert read-modify-write to phy

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Message-ID: <20180104114439.GL28752@n2100.armlinux.org.uk>
Date:   Thu, 4 Jan 2018 11:44:39 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: Issue with commit fea23fb591cc "net: phy: convert
 read-modify-write to phy_modify()"

On Thu, Jan 04, 2018 at 08:00:53AM +0100, Heiner Kallweit wrote:
> Parameter mask of phy_modify() holds the bits to be cleared.
> In the mentioned commit parameter mask seems to be inverted in
> few cases, what IMO is wrong (see example).

I'd be grateful if you could list those that you think are wrong please.

> Maybe I miss something, could you please check?

It's entirely possible that some are wrong - the patch started out as
having the mask argument inverted, but during its evolution, that was
corrected, and I thought all places had been updated - maybe they were
initially wrong.

I did go through the patch several times before sending it to try to
ensure that it was correct, but must have overlooked some, because the
one you quote is one I definitely looked at several times.  It's highly
likely that if I have another look through the patch, I still won't
spot those that you've found.

> And somehow related:
> When adding such helpers, wouldn't it make sense to add
> helpers for setting / clearing bits too? Something like:
> phy_set_bits(phydev, reg, val) -> phy_modify(phydev, reg, 0, val)

Maybe, but lets try and solve the problems with the existing patch
first.

Thanks for reporting this, and sorry for the hassle.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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