linux-kernel - Re: Marking legacy watchdog drivers as deprecated / obsolete

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Message-Id: <201908012358.34991.linux@zary.sk>
Date:   Thu, 1 Aug 2019 23:58:34 +0200
From:   Ondrej Zary <linux@...y.sk>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-watchdog@...r.kernel.org,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Marking legacy watchdog drivers as deprecated / obsolete

On Tuesday 30 July 2019 17:57:37 Guenter Roeck wrote:
> On Tue, Jul 30, 2019 at 10:00:36AM +0200, Arnd Bergmann wrote:
> > On Tue, Jul 30, 2019 at 12:07 AM Guenter Roeck <linux@...ck-us.net> wrote:
> > >
> > > Hi,
> > >
> > > we have recently seen a number of changes to legacy watchdog drivers,
> > > mostly surrounding the coding style used some 10+ years ago, but also
> > > fixing minor formatting or coding problems found by static analyzers.
> > > This slowly rises above the level of background noise.
> > >
> > > Would it be acceptable to mark all those drivers as deprecated/obsolete,
> > > warn users that the driver should be converted to use the watchdog
> > > subsystem, and that it will otherwise be removed in a later Linux kernel
> > > version ? This would give us an idea which drivers are still in use,
> > > and it would enable us to remove the remaining drivers maybe 5 or 6
> > > releases for now.
> > >
> > > Thoughts ?
> > 
> > I don't think an automated approach across 61 drivers is likely to work
> > well. About half of the drivers appear to be for specific SoCs, and
> > removing the watchdog driver while keeping the rest of the SoC support
> > would not be helpful, it  just means we break one of the drivers for the
> > last remaining users of an old SoC the next time they try to upgrade to
> > a new kernel.
> > 
> 
> The primary goal would be to identify drivers still in use, and to trigger
> efforts to convert those drivers to the new infrastructure. Removal of
> obsolete / unused drivers would be a separate decision, to be made at some
> point in the future, and individually for each driver. I specifically wasn't
> trying to suggest auto-removal.
> 
> Guenter
> 
> > It would probably be helpful to go through the list and see if any of
> > the drivers
> > are for platforms that are already gone. FWIW, here is the list of drivers that
> > have their own .ioctl() method, taken from a patch I'm sending soon
> > to add a .compat_ioctl handler:
> > 
> > arch/powerpc/platforms/52xx/mpc52xx_gpt.c
> > arch/um/drivers/harddog_kern.c
> > drivers/char/ipmi/ipmi_watchdog.c
> > drivers/hwmon/fschmd.c
> > drivers/rtc/rtc-ds1374.c
> > drivers/watchdog/acquirewdt.c
> > drivers/watchdog/advantechwdt.c
> > drivers/watchdog/alim1535_wdt.c
> > drivers/watchdog/alim7101_wdt.c
> > drivers/watchdog/ar7_wdt.c
> > drivers/watchdog/at91rm9200_wdt.c
> > drivers/watchdog/ath79_wdt.c
> > drivers/watchdog/bcm63xx_wdt.c
> > drivers/watchdog/cpu5wdt.c
> > drivers/watchdog/eurotechwdt.c
> > drivers/watchdog/f71808e_wdt.c
> > drivers/watchdog/gef_wdt.c
> > drivers/watchdog/geodewdt.c
> > drivers/watchdog/ib700wdt.c
> > drivers/watchdog/ibmasr.c
> > drivers/watchdog/indydog.c
> > drivers/watchdog/intel_scu_watchdog.c
> > drivers/watchdog/iop_wdt.c
> > drivers/watchdog/it8712f_wdt.c
> > drivers/watchdog/ixp4xx_wdt.c
> > drivers/watchdog/ks8695_wdt.c
> > drivers/watchdog/m54xx_wdt.c
> > drivers/watchdog/machzwd.c
> > drivers/watchdog/mixcomwd.c
> > drivers/watchdog/mtx-1_wdt.c
> > drivers/watchdog/mv64x60_wdt.c
> > drivers/watchdog/nuc900_wdt.c
> > drivers/watchdog/nv_tco.c
> > drivers/watchdog/pc87413_wdt.c
> > drivers/watchdog/pcwd.c
> > drivers/watchdog/pcwd_pci.c
> > drivers/watchdog/pcwd_usb.c
> > drivers/watchdog/pika_wdt.c
> > drivers/watchdog/pnx833x_wdt.c
> > drivers/watchdog/rc32434_wdt.c
> > drivers/watchdog/rdc321x_wdt.c
> > drivers/watchdog/riowd.c
> > drivers/watchdog/sa1100_wdt.c
> > drivers/watchdog/sb_wdog.c
> > drivers/watchdog/sbc60xxwdt.c
> > drivers/watchdog/sbc7240_wdt.c
> > drivers/watchdog/sbc_epx_c3.c
> > drivers/watchdog/sbc_fitpc2_wdt.c
> > drivers/watchdog/sc1200wdt.c
> > drivers/watchdog/sc520_wdt.c
> > drivers/watchdog/sch311x_wdt.c
> > drivers/watchdog/scx200_wdt.c
> > drivers/watchdog/smsc37b787_wdt.c
> > drivers/watchdog/w83877f_wdt.c
> > drivers/watchdog/w83977f_wdt.c
> > drivers/watchdog/wafer5823wdt.c
> > drivers/watchdog/wdrtas.c
> > drivers/watchdog/wdt.c
> > drivers/watchdog/wdt285.c
> > drivers/watchdog/wdt977.c
> > drivers/watchdog/wdt_pci.c
> > 
> >       Arnd
> 

I have some older x86 boards so I probably could test some of them. Likely ALi chipset (alim1535_wdt.c and/or alim7101_wdt.c) and some super I/Os (it8712f_wdt.c, w83877f_wdt.c, w83977f_wdt.c).

-- 
Ondrej Zary