linux-kernel - Re: [PATCH v2 7/9] char: misc: Allocate 4 more fixed minors for watchdog

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Message-Id: <ad90af20-33f4-40e3-b08a-ce34437174db@app.fastmail.com>
Date: Tue, 01 Jul 2025 20:45:27 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Zijun Hu" <zijun_hu@...oud.com>,
 "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
 "Jean Delvare" <jdelvare@...e.com>, "Guenter Roeck" <linux@...ck-us.net>,
 "Rudolf Marek" <r.marek@...embler.cz>,
 "Wim Van Sebroeck" <wim@...ux-watchdog.org>,
 "James E . J . Bottomley" <James.Bottomley@...senpartnership.com>,
 "Helge Deller" <deller@....de>, "David S . Miller" <davem@...emloft.net>,
 "Andreas Larsson" <andreas@...sler.com>
Cc: "Thadeu Lima de Souza Cascardo" <cascardo@...lia.com>,
 linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-watchdog@...r.kernel.org, linux-parisc@...r.kernel.org,
 sparclinux@...r.kernel.org, "Zijun Hu" <zijun.hu@....qualcomm.com>
Subject: Re: [PATCH v2 7/9] char: misc: Allocate 4 more fixed minors for watchdog

On Tue, Jul 1, 2025, at 17:24, Zijun Hu wrote:
> From: Zijun Hu <zijun.hu@....qualcomm.com>
>
> There are drivers which needs more fixed minors for watchdog, but
> watchdog only has one fixed minor currently, it causes hardcoded and
> unregistered fixed minors are used by these drivers.
>
> Allocate 4 more fixed minors and apply for these drivers.

Missing signoff?

I don't think this is the right fix here, these drivers implement
the normal watchdog API, so they should not even call misc_register
but should instead call watchdog_dev_register().

Obviously doing this right is a bigger change, so maybe the simpler
answer is to use dynamic minors instead of the nonstandard ones.

FWIW, I double-checked to see whether there are any in-tree
references to these two drivers, and there is one each:

drivers/i2c/busses/i2c-i801.c:	{ "Hermes", DMI_DEV_TYPE_OTHER, 0x73, "fscher" },
drivers/i2c/busses/i2c-i801.c:	{ "Hades",  DMI_DEV_TYPE_OTHER, 0x73, "fschds" },
drivers/i2c/busses/i2c-i801.c:	{ "Syleus", DMI_DEV_TYPE_OTHER, 0x73, "fscsyl" },
arch/powerpc/boot/dts/fsl/t4240rdb.dts:                         compatible = "winbond,w83793";

These were added in 2009 and 2016, respectively, so the hardware
is probably around somewhere but quite hard to find.

    Arnd