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Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support

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On Thu, Nov 10, 2016 at 1:59 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> On Wed, Nov 9, 2016 at 4:43 PM, Rafael J. Wysocki <rafael@kernel.org> wrote:
>> On Mon, Nov 7, 2016 at 10:22 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
>>> As clarified by Rafael at Plumbers, this functional dependencies
>>> framework assumes your driver / subsystem supports deferred probe,
>>
>> It isn't particularly clear what you mean by "support" here.
>
> I noted some folks had reported issues, and you acknowledged that if
> deferred probe was used in some drivers and if this created an issue
> the same issue would be seen with this framework. AFAICT there are two
> possible issues to consider:
>
> 1) the one Geert Uytterhoeven noted. Again I'll note what he had mentioned [0].
>
>   "Some drivers / subsystems don’t support deferred probe yet, such failures
>    usually don’t blow up, but cause subtle malfunctioning. Example, an Ethernet
>    phy could not get its interrupt as the primary IRQ chip had not been probed
>    yet, it reverted to polling though. Sub-optimal." [0]
>
> [0] https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2016-August/003425.html
>
> Geert can you provide more details?

Issue reported in "of_mdiobus_register_phy() and deferred probe"
(http://lkml.iu.edu/hypermail/linux/kernel/1510.2/05770.html)

Key point is:
"However, of_mdiobus_register_phy() uses irq_of_parse_and_map(), which plainly
 ignores EPROBE_DEFER, and it just continues."

At that time, the PHY driver fell back to polling, but as of commit d5c3d8465
("net: phy: Avoid polling PHY with PHY_IGNORE_INTERRUPTS") that's no longer the
case, and now the PHY fails to work completely.

Workaround is "[PATCH v2] irqchip/renesas-irqc: Postpone driver initialization"
(https://www.spinics.net/lists/netdev/msg403325.html), which seems to have
sparked some interest in fixing the issue for good ;-)

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

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Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-27 17:40 +0200
  Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-10-28 12:00 +0200
  Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-07 22:30 +0100
    Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-08 07:50 +0100
      Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-08 20:30 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-08 20:50 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-08 22:00 +0100
            Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 07:50 +0100
              Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Andrzej Hajda <a.hajda@samsung.com> - 2016-11-09 10:40 +0100
                Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 10:50 +0100
    Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-10 01:50 +0100
      Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 02:10 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-11-10 08:20 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 23:10 +0100
            Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-10 23:50 +0100
              Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-11-11 01:10 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Geert Uytterhoeven <geert@linux-m68k.org> - 2016-11-10 09:50 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 23:20 +0100

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