Re: [PATCH 0/6] Marvell MVEBU mbus and Orion GBE driver

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	barebox@lists.infradead.org,
	Michael Grzeschik <mgr@pengutronix.de>
Subject: Re: [PATCH 0/6] Marvell MVEBU mbus and Orion GBE driver
Date: Fri, 7 Feb 2014 10:51:05 +0100	[thread overview]
Message-ID: <20140207095105.GJ16215@pengutronix.de> (raw)
In-Reply-To: <52F4A5DA.2040906@gmail.com>

On Fri, Feb 07, 2014 at 10:22:34AM +0100, Sebastian Hesselbarth wrote:
> On 02/07/2014 08:21 AM, Sascha Hauer wrote:
> >On Wed, Feb 05, 2014 at 11:40:03PM +0100, Sebastian Hesselbarth wrote:
> >>This patch set provides a common driver for the mbus found on all
> >>Marvell MVEBU SoCs and a ethernet driver for the IP found on Marvell
> >>Orion SoCs. Regards go to Michael Grzeschik who forced me to work on
> >>this by importing the borked mv643xx driver from u-boot.
> >>
> >>Compared to the former patches sent by Michael, this driver now
> >>separates mbus handling, mdio bus driver, and ethernet driver. The
> >>mbus handling can be reused on all MVEBU SoCs and is based on what
> >>we already have on Linux for it. The mdio bus driver can be reused
> >>by Armada 370/XP Neta Ethernet core.
> >>
> >>I have tested the driver on SolidRun CuBox (Dove) and also on
> >>Globalscale Guruplug (Kirkwood). Kirkwood still need some loving care
> >>before (88E1121 PHY init, pbl images, ...) so I decided to leave it
> >>out of the patch set for now.
> >>
> >>Patch 1 first reorders drivers/net/{Kconfig,Makefile} alphabetically.
> >>
> >>Patch 2 then introduces a of_phy_device_connect to allow to connect
> >>to a PHY without knowing the corresponding mdio bus.
> >>
> >>Patches 3, 4, 5 add drivers for the mbus, mdio bus, and Orion GBE
> >>respectively.
> >>
> >>Patch 6 finally re-syncs Dove's DT files with v3.14 Linux DT files.
> >>
> >>All patches are based on release v2014.02.0 and can also be found on
> >>https://github.com/shesselba/barebox-dove.git topic/orion-gbe-v1
> >>
> >>Sebastian Hesselbarth (6):
> >>   net: reorder Kconfig and Makefile alphabetically
> >>   net: phy: add of_phy_device_connect
> >>   bus: mvebu: add mbus driver
> >>   net: phy: add mvebu mdio bus driver
> >>   net: orion: add ethernet driver
> >>   ARM: dove: sync with DT files from Linux
> >
> >Looks fine to me except for the two small comments to the mbus driver.
> 
> Sascha,
> 
> actually I forgot to mention that using a separated mdio driver requires
> it to be probed before the eth driver. Right now, this is implicity
> done by reordering the Makefile accordingly.
> 
> This may be fine for now, but I guess there may be some issues in the
> future. Have you thought about deferred probing for barebox, too?

I thought deferred probing, but this requires some work. Right now most
drivers do not release their resources in case of failure. This is fine,
but becomes nasty with deferred probing. Next step would probably be to
introduce devm_ functions to make the error pathes easier. I'm afraid
that deferred probing might become a bottomless pit which makes the
binaries bigger without much gain for most boards.

Right now you're in good company with adjusting the init order, several
other SoCs/boards to that aswell.

Maybe sorting initcalls becomes painful enough that we introduce
deferred probing in future. I still have the dream though that it's
possible to invent some dependency mechanism so that drivers do not
even get probed before all dependencies are there.

Sascha

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