netdev - Re: [PATCH net-next 1/6] net: stmmac: add stmmac_set_tx_clk

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Message-ID: <ZQMizWbkAEyTh4M7@shell.armlinux.org.uk>
Date: Thu, 14 Sep 2023 16:12:13 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Serge Semin <fancer.lancer@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	Alexei Starovoitov <ast@...nel.org>, bpf@...r.kernel.org,
	Daniel Borkmann <daniel@...earbox.net>,
	"David S. Miller" <davem@...emloft.net>,
	Emil Renner Berthing <kernel@...il.dk>,
	Eric Dumazet <edumazet@...gle.com>,
	Fabio Estevam <festevam@...il.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org,
	NXP Linux Team <linux-imx@....com>, Paolo Abeni <pabeni@...hat.com>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Samin Guo <samin.guo@...rfivetech.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Shawn Guo <shawnguo@...nel.org>
Subject: Re: [PATCH net-next 1/6] net: stmmac: add stmmac_set_tx_clk_gmii()

On Thu, Sep 14, 2023 at 05:54:09PM +0300, Serge Semin wrote:
> On Thu, Sep 14, 2023 at 02:51:20PM +0100, Russell King (Oracle) wrote:
> > Add a helper function for setting the transmit clock for GMII
> > interfaces. This handles 1G, 100M and 10M using the standard clock
> > rates of 125MHz, 25MHz and 2.5MHz.
> > 
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> > ---
> >  .../ethernet/stmicro/stmmac/stmmac_platform.c | 25 +++++++++++++++++++
> >  .../ethernet/stmicro/stmmac/stmmac_platform.h |  1 +
> >  2 files changed, 26 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > index 0f28795e581c..f7635ed2b255 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > @@ -700,6 +700,31 @@ EXPORT_SYMBOL_GPL(stmmac_probe_config_dt);
> >  EXPORT_SYMBOL_GPL(devm_stmmac_probe_config_dt);
> >  EXPORT_SYMBOL_GPL(stmmac_remove_config_dt);
> >  
> 
> > +int stmmac_set_tx_clk_gmii(struct clk *tx_clk, unsigned int speed)
> > +{
> > +	unsigned long rate;
> > +
> > +	switch (speed) {
> > +	case SPEED_1000:
> > +		rate = 125000000;
> > +		break;
> > +
> > +	case SPEED_100:
> > +		rate = 25000000;
> > +		break;
> > +
> > +	case SPEED_10:
> > +		rate = 2500000;
> > +		break;
> > +
> > +	default:
> > +		return -ENOTSUPP;
> > +	}
> > +
> > +	return clk_set_rate(tx_clk, rate);
> > +}
> > +EXPORT_SYMBOL_GPL(stmmac_set_tx_clk_gmii);
> 
> As I already noted in v1 normally the switch-case operations are
> defined with no additional line separating the cases. I would have
> dropped them here too especially seeing the stmmac core driver mainly
> follow that implicit convention.

It's rather haphazard whether there are blank lines or not between
case statements.

> Additionally I suggest to move the method to being defined at the head
> of the file. Thus a more natural order normally utilized in the kernel
> drivers would be preserved: all functional implementations go first,
> the platform-specific things are placed below like probe()/remove()
> and their sub-functions, suspend()/resume() and PM descriptors,
> (device IDs table, driver descriptor, etc). stmmac_set_tx_clk_gmii()
> looks as a functional helper which is normally utilized on the network
> device open() stage in the framework of the fix_mac_speed() callback.
> Moreover my suggestion gets to be even more justified seeing you
> placed the method prototype at the head of the prototypes list in the
> stmmac_platform.h file.

How is one supposed to know about this? I did my best trying to work
out where they should've gone...

If it's that important, maybe add some /* Comments */ to state that
there are separate sections to the file?

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