netdev - Re: [PATCH net-next 5/5] net: dsa: mv88e6xxx: move mv88e6xxx_hwtstamp

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Message-ID: <aMmCx1Eu0pDAxWJ9@shell.armlinux.org.uk>
Date: Tue, 16 Sep 2025 16:31:19 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>
Cc: Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>,
	Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH net-next 5/5] net: dsa: mv88e6xxx: move
 mv88e6xxx_hwtstamp_work() prototype

On Tue, Sep 16, 2025 at 02:46:05PM +0200, Andrew Lunn wrote:
> > This leaves the shim definition (for when CONFIG_NET_DSA_MV88E6XXX_PTP
> > is not defined) in ptp.h. It creates an inconsistency and potential
> > problem - the same header should provide all definitions of the same
> > function.
> 
> How big is the PTP code? We have added a lot of code to this driver
> since PTP was added. I suspect the PTP code is now small compared to
> the rest of the driver, so does it still make sense to have it
> optional? Also once the PTP code gets moved into a library and shared
> by the Marvell PHY driver and other Marvell MAC drivers, won't we have
> an overall code shrink even when it is enabled in DSA?
> 
> Maybe it is time for CONFIG_NET_DSA_MV88E6XXX_PTP to go away?

Unmodified:
wc -l:
   611 drivers/net/dsa/mv88e6xxx/hwtstamp.c
   180 drivers/net/dsa/mv88e6xxx/hwtstamp.h
   564 drivers/net/dsa/mv88e6xxx/ptp.c
   176 drivers/net/dsa/mv88e6xxx/ptp.h

size:
   text    data     bss     dec     hex filename
   4004       0      16    4020     fb4 drivers/net/dsa/mv88e6xxx/hwtstamp.o
 130360    3505     224  134089   20bc9 drivers/net/dsa/mv88e6xxx/mv88e6xxx.ko
   3917       0      64    3981     f8d drivers/net/dsa/mv88e6xxx/ptp.o

Current post-conversion:
wc -l:
   459 drivers/net/dsa/mv88e6xxx/hwtstamp.c
   169 drivers/net/dsa/mv88e6xxx/hwtstamp.h
   418 drivers/net/dsa/mv88e6xxx/ptp.c
    83 drivers/net/dsa/mv88e6xxx/ptp.h

size:
   text    data     bss     dec     hex filename
   3988       0       0    3988     f94 drivers/net/dsa/mv88e6xxx/hwtstamp.o
 129312    3505     144  132961   20761 drivers/net/dsa/mv88e6xxx/mv88e6xxx.ko
   2709       0       0    2709     a95 drivers/net/dsa/mv88e6xxx/ptp.o

With a bit more effort to avoid the repeated chip->info->ops->foo
dereferecing chains in ptp.c, I can get this down to:

   text    data     bss     dec     hex filename
   2677       0       0    2677     a75 drivers/net/dsa/mv88e6xxx/ptp.o

So that reduces the PTP .text size by between 31 and 32%.

-- 
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