From: Michael Walle <michael@walle.cc>
To: Lee Jones <lee.jones@linaro.org>
Cc: Frank Rowand <frowand.list@gmail.com>,
andy.shevchenko@gmail.com, robh+dt@kernel.org,
broonie@kernel.org, devicetree@vger.kernel.org,
linus.walleij@linaro.org, linux@roeck-us.net,
andriy.shevchenko@linux.intel.com, robin.murphy@arm.com,
gregkh@linuxfoundation.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] mfd: core: Make a best effort attempt to match devices with the correct of_nodes
Date: Wed, 24 Jun 2020 09:47:20 +0200 [thread overview]
Message-ID: <7a31b34940984b3f0921ed2d4fb29a58@walle.cc> (raw)
In-Reply-To: <20200624064145.GC954398@dell>
Hi,
Am 2020-06-24 08:41, schrieb Lee Jones:
> On Tue, 23 Jun 2020, Frank Rowand wrote:
>
>> On 2020-06-11 14:10, Lee Jones wrote:
>> > Currently, when a child platform device (sometimes referred to as a
>> > sub-device) is registered via the Multi-Functional Device (MFD) API,
>> > the framework attempts to match the newly registered platform device
>> > with its associated Device Tree (OF) node. Until now, the device has
>> > been allocated the first node found with an identical OF compatible
>> > string. Unfortunately, if there are, say for example '3' devices
>> > which are to be handled by the same driver and therefore have the same
>> > compatible string, each of them will be allocated a pointer to the
>> > *first* node.
>>
>> As you mentioned elsewhere in this thread, this series "fixes" the
>> problem related to the "stericsson,ab8500-pwm" compatible.
>>
>> I know, I said I would drop discussion of that compatible, but bear
>> with me for a second. :-)
>>
>> The "problem" is that the devices for multiple mfd child nodes with
>> the same compatible value of "stericsson,ab8500-pwm" will all have
>> a pointer to the first child node. At the moment the same child
>> of_node being used by more than one device does not cause any
>> incorrect behavior.
>>
>> Just in case the driver for "stericsson,ab8500-pwm" is modified
>> in a way that the child of_node needs to be distinct for each
>> device, and that changes gets back ported, it would be useful
>> to have Fixes: tags for this patch series.
>>
>> So, at your discretion (and I'll let you worry about the correct
>> Fixes: tag format), this series fixes:
>>
>> bad76991d7847b7877ae797cc79745d82ffd9120 mfd: Register ab8500 devices
>> using the newly DT:ed MFD API
>
> This patch isn't actually broken.
>
> The issue is the DTB, which [0] addresses.
>
> [0]
> https://lkml.kernel.org/lkml/20200622083432.1491715-1-lee.jones@linaro.org/
Now, I'm confused; because this patch doesn't use the reg property
but a different node name. I'd actually prefer this for any MFD
driver which has multiple nodes of the same compatible string. See
my reasoning here [1]. But until now, no one has responded. Thus,
I'd rather see a OF_MFD_CELL_NAME() which matches the node name
instead of the OF_MFD_CELL_REG() macro.
This would also circumvent the fact that the unit-address has one
number space. Eg. it is not possible to have:
mfd {
compatible = "mfd,compatible";
gpio@0 {
reg = <0>;
};
gpio@1 {
reg = <1>;
};
pwm@0 {
reg = <0>;
};
};
Although Rob mentioned to maybe relax that, but I sill fail to see
the advantage to have an arbitrary reg property instead of a unique
node name.
[1]
https://lore.kernel.org/linux-devicetree/0709f20bc61afb6656bc57312eb69f56@walle.cc/
--
-michael
next prev parent reply other threads:[~2020-06-24 7:47 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 19:10 [PATCH v2 1/3] mfd: core: Make a best effort attempt to match devices with the correct of_nodes Lee Jones
2020-06-11 19:10 ` [PATCH v2 2/3] mfd: core: Fix formatting of MFD helpers Lee Jones
2020-06-12 12:27 ` Frank Rowand
2020-06-11 19:10 ` [PATCH v2 3/3] mfd: core: Add OF_MFD_CELL_REG() helper Lee Jones
2020-06-12 12:28 ` Frank Rowand
2020-06-12 12:26 ` [PATCH v2 1/3] mfd: core: Make a best effort attempt to match devices with the correct of_nodes Frank Rowand
2020-06-15 1:19 ` Frank Rowand
2020-06-15 9:26 ` Lee Jones
2020-06-18 17:34 ` Frank Rowand
2020-06-22 8:50 ` Lee Jones
2020-06-22 14:32 ` Frank Rowand
2020-06-22 14:35 ` Frank Rowand
2020-06-22 15:10 ` Lee Jones
2020-06-22 18:01 ` Frank Rowand
2020-06-22 18:04 ` Frank Rowand
2020-06-22 19:11 ` Lee Jones
2020-06-22 22:23 ` Frank Rowand
2020-06-23 1:17 ` Frank Rowand
2020-06-23 1:37 ` Frank Rowand
2020-06-23 6:47 ` Lee Jones
2020-06-23 17:55 ` Frank Rowand
2020-06-23 19:59 ` Lee Jones
2020-06-23 22:33 ` Frank Rowand
2020-06-24 7:46 ` Lee Jones
2020-06-24 15:51 ` Frank Rowand
2020-06-24 16:14 ` Lee Jones
2020-06-24 16:25 ` Frank Rowand
2020-06-22 8:09 ` Lee Jones
2020-06-22 16:09 ` Frank Rowand
2020-06-22 16:53 ` Lee Jones
2020-06-23 22:21 ` Frank Rowand
2020-06-24 6:45 ` Lee Jones
2020-06-23 23:03 ` Frank Rowand
2020-06-24 6:41 ` Lee Jones
2020-06-24 7:47 ` Michael Walle [this message]
2020-06-24 8:23 ` Lee Jones
2020-06-24 9:19 ` Michael Walle
2020-06-24 11:24 ` Lee Jones
2020-06-11 19:12 Lee Jones
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7a31b34940984b3f0921ed2d4fb29a58@walle.cc \
--to=michael@walle.cc \
--cc=andriy.shevchenko@linux.intel.com \
--cc=andy.shevchenko@gmail.com \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=frowand.list@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=lee.jones@linaro.org \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@roeck-us.net \
--cc=robh+dt@kernel.org \
--cc=robin.murphy@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).