netdev - Re: [PATCH RFC net-next 3/7] net: dsa: use fwnode_get_phy

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Date:   Thu, 23 Mar 2023 15:23:12 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Daniel Scally <djrscally@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Jakub Kicinski <kuba@...nel.org>, linux-acpi@...r.kernel.org,
        netdev@...r.kernel.org, Paolo Abeni <pabeni@...hat.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Vladimir Oltean <olteanv@...il.com>
Subject: Re: [PATCH RFC net-next 3/7] net: dsa: use fwnode_get_phy_mode() to
 get phy interface mode

On Thu, Mar 23, 2023 at 05:00:08PM +0200, Andy Shevchenko wrote:
> On Thu, Mar 23, 2023 at 02:49:01PM +0000, Russell King (Oracle) wrote:
> > On Thu, Mar 23, 2023 at 04:38:29PM +0200, Andy Shevchenko wrote:
> > > On Thu, Mar 23, 2023 at 02:31:04PM +0000, Russell King (Oracle) wrote:
> > > > On Thu, Mar 23, 2023 at 04:03:05PM +0200, Andy Shevchenko wrote:
> > > > > On Wed, Mar 22, 2023 at 12:00:06PM +0000, Russell King (Oracle) wrote:
> 
> ...
> 
> > > > > > +	struct fwnode_handle *fwnode;
> > > > > 
> > > > > > +	fwnode = of_fwnode_handle(dp->dn);
> > > > > 
> > > > > 	const struct fwnode_handle *fwnode = of_fwnode_handle(dp->dn);
> > > > > 
> > > > > ?
> > > > 
> > > > Why const?
> > > 
> > > Do you modify its content on the fly?
> > 
> > Do you want to litter code with casts to get rid of the const?
> > 
> > > For fwnode as a basic object type we want to reduce the scope of the possible
> > > modifications. If you don't modify and APIs you call do not require non-const
> > > object, use const for fwnode.
> > 
> > Let's start here. We pass this fwnode to fwnode_get_phy_mode():
> > 
> > include/linux/property.h:int fwnode_get_phy_mode(struct fwnode_handle *fwnode);
> > 
> > Does fwnode_get_phy_mode() alter the contents of the fwnode? Probably
> > not, but it doesn't take a const pointer. Therefore, to declare my
> > fwnode as const, I'd need to cast the const-ness away before calling
> > this.
> 
> So, fix the fwnode_get_phy_mode(). Is it a problem?

No, I refuse. That's for a different patch set.

> > Then there's phylink_create(). Same problem.
> 
> So, fix that. Is it a problem?

No for the same reason.

> > So NAK to this const - until such time that we have a concerted effort
> > to making functions we call which do not modify the "fwnode" argument
> > constify that argument. Otherwise it's just rediculously crazy to
> > declare a variable const only to then litter the code with casts to get
> > rid of it at every call site.
> > 
> > Please do a bit of research before making suggestions. Thanks.
> 
> So, MAK to your patch. You can fix that, and you know that.

Sorry, I don't accept your NAK. While you have a valid point about
these things being const, that is not the fault of this patch series,
and is something that should be addressed separately.

The lack of const-ness that has been there for quite some time is no
reason to NAK a patch that has nothing to do with this.

> P.S. Please, move that phy thingy away from property.h, it doesn't belong
> there.

Again, that's a subject for a separate patch.

I will re-post this in due course and ignore your NAK (due to your
lack of research, and confrontational nature.)

Thanks.

-- 
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