linux-kernel - Re: [PATCH v5 net-next 2/2] net: phy: micrel: Fix warn: passing zero to PTR

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Date:   Tue, 6 Dec 2022 15:08:59 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Divya.Koppera@...rochip.com
Cc:     hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        richardcochran@...il.com, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v5 net-next 2/2] net: phy: micrel: Fix warn: passing zero
 to PTR_ERR

> > > -     if (!IS_ENABLED(CONFIG_PTP_1588_CLOCK) ||
> > > -         !IS_ENABLED(CONFIG_NETWORK_PHY_TIMESTAMPING))
> > > -             return 0;
> > > -
> > 
> > Why are you removing this ?
> > 
> 
> I got review comment from Richard in v2 as below, making it as consistent by checking ptp_clock. So removed it in next revision.
> 
> " > static int lan8814_ptp_probe_once(struct phy_device *phydev)
> > {
> >         struct lan8814_shared_priv *shared = phydev->shared->priv;
> > 
> >         if (!IS_ENABLED(CONFIG_PTP_1588_CLOCK) ||
> >             !IS_ENABLED(CONFIG_NETWORK_PHY_TIMESTAMPING))
> >                 return 0;
> 
> It is weird to use macros here, but not before calling ptp_clock_register.
> Make it consistent by checking shared->ptp_clock instead.
> That is also better form."

O.K. If Richard said this fine.

Just out of interest, could you disassemble lan8814_ptp_probe_once()
when CONFIG_PTP_1588_CLOCK is disabled, with and without this check?

My guess is, when PTP is disabled, the mutex still gets initialised,
all the member of shared->ptp_clock_info are set. The optimise cannot
remove it. With the macro check, the function is empty. So you end up
with a slightly bigger text size.

       Andrew