From: Jakub Kicinski <kuba@kernel.org>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: "David S . Miller" <davem@davemloft.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"UNGLinuxDriver@microchip.com" <UNGLinuxDriver@microchip.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Vivien Didelot <vivien.didelot@gmail.com>,
Horatiu Vultur <horatiu.vultur@microchip.com>,
"Allan W . Nielsen" <allan.nielsen@microchip.com>,
Claudiu Manoil <claudiu.manoil@nxp.com>,
Steen Hegelund <steen.hegelund@microchip.com>
Subject: Re: [PATCH v2 net] net: mscc: ocelot: install MAC addresses in .ndo_set_rx_mode from process context
Date: Fri, 4 Dec 2020 16:41:01 -0800 [thread overview]
Message-ID: <20201204164101.67d3d370@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> (raw)
In-Reply-To: <20201204192310.al6fhkbarhbjng3a@skbuf>
On Fri, 4 Dec 2020 19:23:11 +0000 Vladimir Oltean wrote:
> > > > What's the expected poll time? maybe it's not that bad to busy wait?
> > > > Clearly nobody noticed the issue in 2 years (you mention lockdep so
> > > > not a "real" deadlock) which makes me think the wait can't be that long?
> > >
> > > Not too much, but the sleep is there.
> > > Also, all 3 of ocelot/felix/seville are memory-mapped devices. But I
> > > heard from Alex a while ago that he intends to add support for a switch
> > > managed over a slow bus like SPI, and to use the same regmap infrastructure.
> > > That would mean that this problem would need to be resolved anyway.
> >
> > So it's MMIO but the other end is some firmware running on the device?
>
> No. It's always register-based access, just that in some cases the
> registers are directly memory-mapped for Linux, while in other cases
> they are beyond an SPI bus. But there isn't any firmware in any case.
I see, so ocelot_mact_wait_for_completion() waits for some hardware
engine to process the command? It looked like FW is hiding behind that
register at a glance. 100ms sounds very high for hardware processing.
next prev parent reply other threads:[~2020-12-05 0:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-04 17:51 [PATCH v2 net] net: mscc: ocelot: install MAC addresses in .ndo_set_rx_mode from process context Vladimir Oltean
2020-12-04 18:00 ` Jakub Kicinski
2020-12-04 18:12 ` Vladimir Oltean
2020-12-04 18:15 ` Alexandre Belloni
2020-12-04 18:55 ` Jakub Kicinski
2020-12-04 19:23 ` Vladimir Oltean
2020-12-05 0:41 ` Jakub Kicinski [this message]
2020-12-04 19:24 ` Jakub Kicinski
2020-12-04 19:26 ` Alexandre Belloni
2020-12-04 18:25 ` Vladimir Oltean
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