From: Maxime Ripard <maxime.ripard@bootlin.com>
To: "Rodrigo Exterckötter Tjäder" <rodrigo@tjader.xyz>
Cc: wens@csie.org, robh+dt@kernel.org, mark.rutland@arm.com,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64: dts: allwinner: Olimex A64-OLinuXino: enable eMMC.
Date: Sat, 29 Sep 2018 17:47:54 +0200 [thread overview]
Message-ID: <20180929154754.abz3byvrufvnf4dq@flea> (raw)
In-Reply-To: <CAG7TQgGMkvBnNE_WEth8gscKxN3qN8a44mNMWz3QP-2+JKfOzg@mail.gmail.com>
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On Thu, Sep 27, 2018 at 11:49:20AM -0300, Rodrigo Exterckötter Tjäder wrote:
> On Thu, Sep 27, 2018 at 5:17 AM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> >
> > On Tue, Sep 25, 2018 at 02:47:59PM -0300, Rodrigo Exterckötter Tjäder wrote:
> > > On Tue, Sep 25, 2018 at 6:01 AM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > > > We can't really do that, unfortunately. If the device tree name was to
> > > > change for a given board, we'd break all the build systems, boot
> > > > scripts and distros out there.
> > >
> > > What if we keep the device tree for the version without WiFi and eMMC
> > > with the current name and create new device trees for the other two
> > > versions?
> >
> > Wifi and Bluetooth should be dealt with with overlays in this case,
> > and since the eMMC is already enabled, then there's nothing to do, I
> > guess.
>
> It's WiFi that is already enabled, not eMMC. Only one of the three
> variants has WiFi.
Ah, right, sorry. In the board that doesn't have an emmc, are the pins
usable for something else?
> We can't even remove a node from a device tree? Removing the WiFi node
> from the current tree would make it correspond to the variant with the
> least features.
Not really. How pissed would you be if you were a user, had wifi
running on your board, you upgrade your kernel, and then it's just
gone? :)
> About device tree overlays, I read overlay-notes.txt, but I went
> looking for an example with "git grep /plugin/ arch" and it came
> empty. Is this approach not used for other boards?
It is, it's simply not stored in the kernel, but through other third
party repos.
> Does the overlay approach make the device available at boot time? That
> is important for a storage device such as eMMC.
>
> I went with the separate dts approach because that's what I saw was
> done for other similar cases, like Pine64 and Pine64+, OLinuXino-LIME2
> and its variant with eMMC, among others.
Yeah, but in all these cases, it was done from day one, not after the
facts.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2018-09-29 15:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-19 14:18 [PATCH 1/2] arm64: dts: allwinner: Olimex A64-OLinuXino: enable eMMC Rodrigo Exterckötter Tjäder
2018-09-21 14:28 ` Maxime Ripard
2018-09-21 14:54 ` Rodrigo Exterckötter Tjäder
2018-09-25 9:01 ` Maxime Ripard
2018-09-25 17:47 ` Rodrigo Exterckötter Tjäder
2018-09-27 8:17 ` Maxime Ripard
2018-09-27 14:49 ` Rodrigo Exterckötter Tjäder
2018-09-29 15:47 ` Maxime Ripard [this message]
2018-09-29 16:51 ` Rodrigo Exterckötter Tjäder
2018-10-02 13:13 ` Maxime Ripard
2018-10-02 16:47 ` Rodrigo Exterckötter Tjäder
2018-10-05 15:48 ` Maxime Ripard
2018-11-15 14:46 ` Rodrigo Exterckötter Tjäder
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