From: Ansuel Smith <ansuelsmth@gmail.com>
To: "Marek Behún" <kabel@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Vladimir Oltean <olteanv@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Jonathan Corbet <corbet@lwn.net>, Pavel Machek <pavel@ucw.cz>,
John Crispin <john@phrozen.org>,
netdev@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-leds@vger.kernel.org
Subject: Re: [RFC PATCH v2 1/5] leds: trigger: add API for HW offloading of triggers
Date: Mon, 8 Nov 2021 21:15:06 +0100 [thread overview]
Message-ID: <YYmFSsQ9Iz7DDXb0@Ansuel-xps.localdomain> (raw)
In-Reply-To: <20211108211110.4ad78e41@thinkpad>
On Mon, Nov 08, 2021 at 09:11:10PM +0100, Marek Behún wrote:
> On Mon, 8 Nov 2021 20:53:36 +0100
> Andrew Lunn <andrew@lunn.ch> wrote:
>
> > > I guess I will have to work on this again ASAP or we will end up with
> > > solution that I don't like.
> > >
> > > Nonetheless, what is your opinion about offloading netdev trigger vs
> > > introducing another trigger?
> >
> > It is a solution that fits the general pattern, do it in software, and
> > offload it if possible.
> >
> > However, i'm not sure the software solution actually works very well.
> > At least for switches. The two DSA drivers which implement
> > get_stats64() simply copy the cached statistics. The XRS700X updates
> > its cached values every 3000ms. The ar9331 is the same. Those are the
> > only two switch drivers which implement get_stats64 and none implement
> > get_stats. There was also was an issue that get_stats64() cannot
> > perform blocking calls. I don't remember if that was fixed, but if
> > not, get_stats64() is going to be pretty useless on switches.
> >
> > We also need to handle drivers which don't actually implement
> > dev_get_stats(). That probably means only supporting offloads, all
> > modes which cannot be offloaded need to be rejected. This is pretty
> > much the same case of software control of the LEDs is not possible.
> > Unfortunately, dev_get_stats() does not return -EOPNOTSUPP, you need
> > to look at dev->netdev_ops->ndo_get_stats64 and
> > dev->netdev_ops->ndo_get_stats.
> >
> > Are you working on Marvell switches? Have you implemented
> > get_stats64() for mv88e6xxx? How often do you poll the hardware for
> > the stats?
> >
> > Given this, i think we need to bias the API so that it very likely
> > ends up offloading, if offloading is available.
>
> I am working with Marvell PHYs and Marvell switches. I am aware of the
> problem that SW netdev does not work for switches because we don't have
> uptodate data.
>
> It seems to me that yes, if the user wants to blink the LEDs on
> activity on switch port, the netdev trigger should only work in offload
> mode and only on LEDs that are connected to switch pins, unless we
> implement a mechanism to get statistics at lest 10 times a second
> (which could maybe be done on marvell switches by reading the registers
> via ethernet frames instead of MDIO).
>
> Marvell switches don't seem to support rx only / tx only activity
> blinking, only rx/tx. I think this could be solved by making rx/tx
> sysfs files for netdev trigger behave so that writing to one would also
> write to another.
>
> But since currently netdev trigger does not work for these switches, I
> think making it so that it works at least to some fashion (in HW
> supported modes) would still be better that current situation.
>
> I will try to look into this, maybe work together with Ansuel.
>
> Marek
I'm polishing some api with Andrew comments and will try to extend
netdev trigger while still proposing the additional trigger. Better
discuss in v3.
I think the main target here is first have a good generic solution for
offload and then actually thinking about working on the triggers/offload
part.
--
Ansuel
next prev parent reply other threads:[~2021-11-08 20:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-08 0:24 [RFC PATCH v2 0/5] Adds support for PHY LEDs with offload triggers Ansuel Smith
2021-11-08 0:24 ` [RFC PATCH v2 1/5] leds: trigger: add API for HW offloading of triggers Ansuel Smith
2021-11-08 2:29 ` Randy Dunlap
2021-11-08 14:04 ` Andrew Lunn
2021-11-08 15:16 ` Ansuel Smith
2021-11-08 16:13 ` Marek Behún
2021-11-08 16:46 ` Ansuel Smith
2021-11-08 17:35 ` Marek Behún
2021-11-08 17:58 ` Ansuel Smith
2021-11-08 18:41 ` Marek Behún
2021-11-08 19:08 ` Ansuel Smith
2021-11-08 19:17 ` Marek Behún
2021-11-08 17:46 ` Andrew Lunn
2021-11-08 17:56 ` Marek Behún
2021-11-08 19:53 ` Andrew Lunn
2021-11-08 20:03 ` Vladimir Oltean
2021-11-08 20:11 ` Marek Behún
2021-11-08 20:15 ` Ansuel Smith [this message]
2021-11-08 17:37 ` Andrew Lunn
2021-11-08 0:24 ` [RFC PATCH v2 2/5] leds: add function to configure offload leds Ansuel Smith
2021-11-08 2:22 ` Randy Dunlap
2021-11-08 0:24 ` [RFC PATCH v2 3/5] leds: trigger: add offload-phy-activity trigger Ansuel Smith
2021-11-08 2:24 ` Randy Dunlap
2021-11-08 14:17 ` Andrew Lunn
2021-11-08 15:19 ` Ansuel Smith
2021-11-08 0:24 ` [RFC PATCH v2 4/5] net: dsa: qca8k: add LEDs support Ansuel Smith
2021-11-08 2:26 ` Randy Dunlap
2021-11-08 0:25 ` [RFC PATCH v2 5/5] dt-bindings: net: dsa: qca8k: add LEDs definition example Ansuel Smith
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