From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"Kieran Bingham" <kieran@ksquared.org.uk>,
"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Jacopo Mondi" <jacopo@jmondi.org>,
"Vladimir Zapolskiy" <vz@mleia.com>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Linux I2C" <linux-i2c@vger.kernel.org>,
"Luca Ceresoli" <luca@lucaceresoli.net>,
linux-i3c@lists.infradead.org,
"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>
Subject: Re: [RFC PATCH 3/7] i2c: allow DT nodes without 'compatible'
Date: Thu, 12 Mar 2020 12:44:32 +0100 [thread overview]
Message-ID: <20200312114432.GA3384@piout.net> (raw)
In-Reply-To: <20200312111950.GA1013@ninjato>
On 12/03/2020 12:19:51+0100, Wolfram Sang wrote:
> > Clearly this does not fit the case reported by Alexandre: a device
> > having a driver which is known to be badly buggy, so we don't want to
> > instantiate it. But again, this should not affect DT as it is not
> > describing the HW, but only an implementation detail. Probably disabling
> > or blacklisting the driver would be a better option there?
>
> "Fixing the driver" is the first thing coming to my mind ;) But yeah,
> blacklisting would be another good solution. With only the information
> above, DT is not the right place to fix a broken driver.
>
To be clear, the driver is working properly but the HW isn't. It is a
PMIC and we need to avoid linux talking to it so the PMIC doesn't end up
killing the bus.
We end up with a node properly described in the device tree but with
status = "disabled". The relevance to the discussion was that you know
what is there and you want to avoid using its address.
See the pmic node on i2c1 in arch/arm/boot/dts/at91-sama5d3_xplained.dts
for what I'm referring to.
> > My apologies to Wolfram, I appreciate a lot the effort you are doing,
> > but before reviewing this patch I have never realized what I tried to
> > explain above.
>
> All good, Luca! Talking over code usually brings in viewpoints which
> have been missed so far. This is expected. Actually, I am very happy to
> have this discussion!
>
> All the best,
>
> Wolfram
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2020-03-13 8:54 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 17:23 [RFC PATCH 0/7] i2c: of: reserve unknown and ancillary addresses Wolfram Sang
2020-02-20 17:23 ` [RFC PATCH 1/7] i2c: add sanity check for parameter of i2c_verify_client() Wolfram Sang
2020-02-21 9:36 ` Geert Uytterhoeven
2020-02-20 17:23 ` [RFC PATCH 2/7] i2c: use DEFINE for the dummy driver name Wolfram Sang
2020-02-21 9:38 ` Geert Uytterhoeven
2020-02-20 17:23 ` [RFC PATCH 3/7] i2c: allow DT nodes without 'compatible' Wolfram Sang
2020-02-21 9:45 ` Geert Uytterhoeven
2020-02-21 9:48 ` Geert Uytterhoeven
2020-02-23 23:11 ` Luca Ceresoli
2020-03-12 11:19 ` Wolfram Sang
2020-03-12 11:44 ` Alexandre Belloni [this message]
2020-04-10 13:47 ` Luca Ceresoli
2020-02-26 16:30 ` Rob Herring
2020-02-20 17:24 ` [RFC PATCH 4/7] i2c: of: remove superfluous parameter from exported function Wolfram Sang
2020-02-21 9:50 ` Geert Uytterhoeven
2020-02-24 8:12 ` Luca Ceresoli
2020-02-20 17:24 ` [RFC PATCH 5/7] i2c: of: error message unification Wolfram Sang
2020-02-21 9:54 ` Geert Uytterhoeven
2020-02-20 17:24 ` [RFC PATCH 6/7] i2c: of: mark a whole array of regs as reserved Wolfram Sang
2020-02-21 10:09 ` Geert Uytterhoeven
2020-03-12 11:21 ` Wolfram Sang
2020-03-18 14:33 ` Wolfram Sang
2020-02-28 12:11 ` Luca Ceresoli
2020-02-20 17:24 ` [RFC PATCH 7/7] i2c: core: hand over reserved devices when requesting ancillary addresses Wolfram Sang
2020-02-21 10:13 ` Geert Uytterhoeven
2020-02-28 12:11 ` Luca Ceresoli
2020-03-12 11:30 ` Wolfram Sang
2020-03-12 11:21 ` Wolfram Sang
2020-03-13 12:42 ` Wolfram Sang
2020-02-21 10:15 ` [RFC PATCH 0/7] i2c: of: reserve unknown and " Geert Uytterhoeven
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