netdev - Re: [net-next PATCH 13/14] net: phy: qcom: deatch qca83xx PHY driver from at803x

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Message-ID: <ZWceeQFBSZD1hzSk@shell.armlinux.org.uk>
Date: Wed, 29 Nov 2023 11:20:25 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Andy Gross <agross@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [net-next PATCH 13/14] net: phy: qcom: deatch qca83xx PHY driver
 from at803x

On Wed, Nov 29, 2023 at 11:37:56AM +0100, Christian Marangi wrote:
> On Wed, Nov 29, 2023 at 09:53:00AM +0000, Russell King (Oracle) wrote:
> > On Wed, Nov 29, 2023 at 03:12:18AM +0100, Christian Marangi wrote:
> > > diff --git a/drivers/net/phy/qcom/Makefile b/drivers/net/phy/qcom/Makefile
> > > index 6a68da8aaa7b..43e4d14df8ea 100644
> > > --- a/drivers/net/phy/qcom/Makefile
> > > +++ b/drivers/net/phy/qcom/Makefile
> > > @@ -1,2 +1,3 @@
> > >  # SPDX-License-Identifier: GPL-2.0
> > > -obj-$(CONFIG_AT803X_PHY)	+= at803x.o
> > > +obj-$(CONFIG_AT803X_PHY)	+= at803x.o common.o
> > > +obj-$(CONFIG_QCA83XX_PHY)	+= qca83xx.o common.o
> > 
> > These PHY drivers can be built as modules. You will end up with several
> > modules - at803x.ko, qca83xx.ko and common.ko. You don't mark any
> > functions in common.c as exported, no module license, no author, no
> > description. common.ko is way too generic a name as well.
> > 
> > Please think about this more and test building these drivers as a
> > module.
> >
> 
> Had some fear about this...
> 
> What would be the preferred way for this?
> 
> Having a .ko that EXPORT symbol or making the PHY driver .ko to compile
> the common.o in it?

I think the former, otherwise we end up with common.o duplicated in
each module, which becomes unnecessary bloat. This is how the Broadcom
stuff (which also has a "library") does it.

> Honestly I would like the second option since I would prefer not to
> create a .ko with shared function and EXPORT lots of symbols. On SoC it's
> expected to have only one of the PHY (at max 2 when the qca807x PHY will
> be implemented, with the at808x also present) so the size increase is
> minimal.
> 
> (just to be more clear, talking about this makefile implementation)
> 
> at803x-objs			+= common.o
> obj-$(CONFIG_AT803X_PHY)	+= at803x.o
> qca83xx-objs			+= common.o
> obj-$(CONFIG_QCA83XX_PHY)	+= qca83xx.o
> qca808x-objs			+= common.o
> obj-$(CONFIG_QCA808X_PHY)	+= qca808x.o

That won't work - the -objs needs to list the corresponding .o file
as well, and it needs to be a different name (you can't do this:

qca808x-objs			+= common.o qca808x.o

it has to be something like:

qca808x-phy-objs		+= common.o qca808x.o
obj-$(CONFIG_QCA808X_PHY)	+= qca808x-phy.o

However, I don't like this because it means each module ends up with
a copy of common.o in it.

> For name of common.c, is qcom_ethphy_common.c a better name?

or qcom-phy-lib.c which follows what we have for Broadcom.

-- 
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