From: Vladimir Oltean <olteanv@gmail.com>
To: Ansuel Smith <ansuelsmth@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [net-next PATCH 1/4] drivers: net: dsa: qca8k: drop MTU tracking from qca8k_priv
Date: Tue, 22 Mar 2022 15:55:35 +0200 [thread overview]
Message-ID: <20220322135535.au5d2n7hcu4mfdxr@skbuf> (raw)
In-Reply-To: <YjnRQNg/Do0SwNq/@Ansuel-xps.localdomain>
On Tue, Mar 22, 2022 at 02:38:08PM +0100, Ansuel Smith wrote:
> On Tue, Mar 22, 2022 at 01:58:12PM +0200, Vladimir Oltean wrote:
> > On Tue, Mar 22, 2022 at 02:45:03AM +0100, Ansuel Smith wrote:
> > > Drop the MTU array from qca8k_priv and use slave net dev to get the max
> > > MTU across all user port. CPU port can be skipped as DSA already make
> > > sure CPU port are set to the max MTU across all ports.
> > >
> > > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> > > ---
> >
> > I hardly find this to be an improvement and I would rather not see such
> > unjustified complexity in a device driver. What are the concrete
> > benefits, size wise?
> >
>
> The main idea here is, if the value is already present and accessible,
> why should we duplicate it? Tracking the MTU in this custom way already
> caused some bugs (check the comment i'm removing). We both use standard
> way to track ports MTU and we save some additional space. At the cost of
> 2 additional checks are are not that much of a problem.
Where is the bug?
> Also from this I discovered that (at least on ipq806x that use stmmac)
> when master needs to change MTU, stmmac complains that the interface is
> up and it must be put down. Wonder if that's common across other drivers
> or it's only specific to stmmac.
I never had the pleasure of dealing with such DSA masters. I wonder why
can't stmmac_change_mtu() check if netif_running(), call dev_close and
set a bool, and at the end, if the bool was set, call dev_open back?
next prev parent reply other threads:[~2022-03-22 13:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 1:45 [net-next PATCH 0/4] Reduce qca8k_priv space usage Ansuel Smith
2022-03-22 1:45 ` [net-next PATCH 1/4] drivers: net: dsa: qca8k: drop MTU tracking from qca8k_priv Ansuel Smith
2022-03-22 11:58 ` Vladimir Oltean
2022-03-22 13:38 ` Ansuel Smith
2022-03-22 13:55 ` Vladimir Oltean [this message]
2022-03-22 14:03 ` Ansuel Smith
2022-03-24 10:45 ` Vladimir Oltean
2022-03-24 20:44 ` Ansuel Smith
2022-03-24 21:05 ` Vladimir Oltean
2022-03-24 23:10 ` Ansuel Smith
2022-03-24 23:14 ` Vladimir Oltean
2022-03-24 23:24 ` Ansuel Smith
2022-03-22 1:45 ` [net-next PATCH 2/4] drivers: net: dsa: qca8k: drop port_sts " Ansuel Smith
2022-03-22 1:45 ` [net-next PATCH 3/4] drivers: net: dsa: qca8k: rework and simplify mdiobus logic Ansuel Smith
2022-03-22 1:45 ` [net-next PATCH 4/4] drivers: net: dsa: qca8k: drop dsa_switch_ops from qca8k_priv Ansuel Smith
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