From: Andrew Lunn <andrew@lunn.ch>
To: "Petr Štetiar" <ynezz@true.cz>
Cc: netdev@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Nicolas Ferre <nicolas.ferre@microchip.com>,
"David S. Miller" <davem@davemloft.net>,
Florian Fainelli <f.fainelli@gmail.com>,
Heiner Kallweit <hkallweit1@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Maxime Ripard <maxime.ripard@bootlin.com>,
Alban Bedel <albeu@free.fr>
Subject: Re: Handling of EPROBE_DEFER in of_get_mac_address [Was: Re: [PATCH v2 3/4] net: macb: Drop nvmem_get_mac_address usage]
Date: Wed, 1 May 2019 15:54:17 +0200 [thread overview]
Message-ID: <20190501135417.GB19809@lunn.ch> (raw)
In-Reply-To: <20190430141335.GC346@meh.true.cz>
On Tue, Apr 30, 2019 at 04:13:35PM +0200, Petr Štetiar wrote:
> Andrew Lunn <andrew@lunn.ch> [2019-04-29 15:02:48]:
>
> Hi Andrew,
>
> > > My understanding of -PROBE_DEFER is, that it needs to be propagated back from
> > > the driver's probe callback/hook to the upper device/driver subsystem in order
> > > to be moved to the list of pending drivers and considered for probe later
> > > again. This is not going to happen in any of the current drivers, thus it will
> > > probably still always result in random MAC address in case of -EPROBE_DEFER
> > > error from the nvmem subsystem.
> >
> > All current drivers which don't look in NVMEM don't expect
> > EPROBE_DEFER.
>
> once there's NVMEM wired in of_get_mac_address, one can simply use it, nothing
> is going to stop the potential user of doing so and if EPROBE_DEFER isn't
> propagated from the driver back to the upper device driver subsytem, it's
> probably going to end with random MAC address in some (very rare?) cases.
Hi Petr
There is no simple answer here. If we add EPROBE_DEFER support to all
the current drivers using of_get_mac_address(), we are likely to break
something. Regressions are bad. If somebody does add NVMEM properties
to a device which does not currently have them, and it fails, that it
just bad testing, not a regressions.
So i would keep it KISS. Allow of_get_mac_address() to return an
error, but don't modify current drivers to look for it.
Andrew
next prev parent reply other threads:[~2019-05-01 13:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-28 12:53 [PATCH v2 0/4] of_net: Add NVMEM support to of_get_mac_address Petr Štetiar
2019-04-28 12:53 ` [PATCH v2 1/4] " Petr Štetiar
2019-05-01 20:19 ` Rob Herring
2019-05-02 9:05 ` Petr Štetiar
2019-05-07 16:06 ` Rob Herring
2019-05-08 9:02 ` Petr Štetiar
2019-04-28 12:53 ` [PATCH v2 2/4] dt-bindings: doc: Reflect new NVMEM of_get_mac_address behaviour Petr Štetiar
2019-04-28 16:53 ` Andrew Lunn
2019-05-01 20:22 ` Rob Herring
2019-04-28 12:53 ` [PATCH v2 3/4] net: macb: Drop nvmem_get_mac_address usage Petr Štetiar
2019-04-28 16:56 ` Andrew Lunn
2019-04-28 21:08 ` Petr Štetiar
2019-04-28 21:36 ` Andrew Lunn
2019-04-29 7:55 ` Petr Štetiar
2019-04-29 13:02 ` Andrew Lunn
2019-04-30 14:13 ` Handling of EPROBE_DEFER in of_get_mac_address [Was: Re: [PATCH v2 3/4] net: macb: Drop nvmem_get_mac_address usage] Petr Štetiar
2019-05-01 13:54 ` Andrew Lunn [this message]
2019-04-28 12:53 ` [PATCH v2 4/4] net: davinci_emac: Drop nvmem_get_mac_address usage Petr Štetiar
2019-04-28 16:58 ` Andrew Lunn
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