From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Clay McClure <clay@daemons.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
Richard Cochran <richardcochran@gmail.com>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Vladimir Oltean <olteanv@gmail.com>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Jakub Kicinski <kuba@kernel.org>,
Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>,
Mao Wenan <maowenan@huawei.com>,
Linus Walleij <linus.walleij@linaro.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Edward Cree <ecree@solarflare.com>,
Nicolas Pitre <nico@fluxnic.net>,
Josh Triplett <josh@joshtriplett.org>,
netdev <netdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: Select PTP_1588_CLOCK in PTP-specific drivers
Date: Tue, 28 Apr 2020 11:21:15 +0200 [thread overview]
Message-ID: <CAMuHMdXhVcp3j4Sq_4fsqavw1eH_DksN-yjajqC_8pRKnjM0zA@mail.gmail.com> (raw)
In-Reply-To: <20200428090749.31983-1-clay@daemons.net>
Hi Clay,
Thanks for your patch!
On Tue, Apr 28, 2020 at 11:14 AM Clay McClure <clay@daemons.net> wrote:
> Commit d1cbfd771ce8 ("ptp_clock: Allow for it to be optional") changed
> all PTP-capable Ethernet drivers from `select PTP_1588_CLOCK` to `imply
> PTP_1588_CLOCK`, "in order to break the hard dependency between the PTP
> clock subsystem and ethernet drivers capable of being clock providers."
> As a result it is possible to build PTP-capable Ethernet drivers without
> the PTP subsystem by deselecting PTP_1588_CLOCK. Drivers are required to
> handle the missing dependency gracefully.
>
> Some PTP-capable Ethernet drivers (e.g., TI_CPSW) factor their PTP code
> out into separate drivers (e.g., TI_CPTS_MOD). The above commit also
> changed these PTP-specific drivers to `imply PTP_1588_CLOCK`, making it
> possible to build them without the PTP subsystem. But as Grygorii
> Strashko noted in [1]:
>
> On Wed, Apr 22, 2020 at 02:16:11PM +0300, Grygorii Strashko wrote:
>
> > Another question is that CPTS completely nonfunctional in this case and
> > it was never expected that somebody will even try to use/run such
> > configuration (except for random build purposes).
>
> In my view, enabling a PTP-specific driver without the PTP subsystem is
> a configuration error made possible by the above commit. Kconfig should
> not allow users to create a configuration with missing dependencies that
> results in "completely nonfunctional" drivers.
>
> I audited all network drivers that call ptp_clock_register() and found
> six that look like PTP-specific drivers that are likely nonfunctional
> without PTP_1588_CLOCK:
>
> NET_DSA_MV88E6XXX_PTP
> NET_DSA_SJA1105_PTP
> MACB_USE_HWSTAMP
> CAVIUM_PTP
> TI_CPTS_MOD
> PTP_1588_CLOCK_IXP46X
>
> Note how they all reference PTP or timestamping in their name; this is a
> clue that they depend on PTP_1588_CLOCK.
>
> Change these drivers back [2] to `select PTP_1588_CLOCK`. Note that this
> requires also selecting POSIX_TIMERS, a transitive dependency of
> PTP_1588_CLOCK.
If these drivers have a hard dependency on PTP_1588_CLOCK, IMHO they
should depend on PTP_1588_CLOCK, not select PTP_1588_CLOCK.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-04-28 9:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 9:07 [PATCH] net: Select PTP_1588_CLOCK in PTP-specific drivers Clay McClure
2020-04-28 9:21 ` Geert Uytterhoeven [this message]
2020-04-28 16:07 ` Arnd Bergmann
2020-04-29 7:29 ` Clay McClure
2020-04-29 7:59 ` [PATCH v2] net: Make PTP-specific drivers depend on PTP_1588_CLOCK Clay McClure
2020-05-01 22:28 ` David Miller
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=CAMuHMdXhVcp3j4Sq_4fsqavw1eH_DksN-yjajqC_8pRKnjM0zA@mail.gmail.com \
--to=geert@linux-m68k.org \
--cc=andrew@lunn.ch \
--cc=arnd@arndb.de \
--cc=brouer@redhat.com \
--cc=clay@daemons.net \
--cc=davem@davemloft.net \
--cc=ecree@solarflare.com \
--cc=f.fainelli@gmail.com \
--cc=geert+renesas@glider.be \
--cc=gregkh@linuxfoundation.org \
--cc=grygorii.strashko@ti.com \
--cc=ilias.apalodimas@linaro.org \
--cc=ivan.khoronzhuk@linaro.org \
--cc=josh@joshtriplett.org \
--cc=kuba@kernel.org \
--cc=linus.walleij@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maowenan@huawei.com \
--cc=netdev@vger.kernel.org \
--cc=nico@fluxnic.net \
--cc=nicolas.ferre@microchip.com \
--cc=nicolas.pitre@linaro.org \
--cc=olteanv@gmail.com \
--cc=richardcochran@gmail.com \
--cc=tglx@linutronix.de \
--cc=vivien.didelot@gmail.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).