linux-kernel - Re: [PATCH v8 05/26] clocksource: Add driver for the Ingenic JZ47xx OST

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Message-Id: <1550891845.20534.1@crapouillou.net>
Date:   Sat, 23 Feb 2019 00:17:25 -0300
From:   Paul Cercueil <paul@...pouillou.net>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Mathieu Malaterre <malat@...ian.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Ezequiel Garcia <ezequiel@...labora.co.uk>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
        linux-pwm@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        linux-watchdog@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-clk@...r.kernel.org, od@...c.me,
        Maarten ter Huurne <maarten@...ewalker.org>
Subject: Re: [PATCH v8 05/26] clocksource: Add driver for the Ingenic JZ47xx
 OST

Hi,

Le jeu. 24 janv. 2019 à 19:53, Paul Cercueil <paul@...pouillou.net> a 
écrit :
> 
> 
> Le jeu. 24 janv. 2019 à 19:46, Stephen Boyd <sboyd@...nel.org> a 
> écrit :
>> Quoting Paul Cercueil (2019-01-24 12:46:28)
>>> 
>>> 
>>>  Le jeu. 24 janv. 2019 à 16:28, Stephen Boyd <sboyd@...nel.org> a
>>>  écrit :
>>>  > Quoting Guenter Roeck (2019-01-23 10:01:55)
>>>  >>  On Wed, Jan 23, 2019 at 02:25:53PM -0300, Paul Cercueil wrote:
>>>  >>  > Hi,
>>>  >>  >
>>>  >>  > Le mer. 23 janv. 2019 Ã  11:31, Guenter Roeck
>>>  >> <linux@...ck-us.net> a Ã©crit :
>>>  >>  > >On 1/23/19 4:58 AM, Mathieu Malaterre wrote:
>>>  >>  > >>On Wed, Dec 12, 2018 at 11:09 PM Paul Cercueil
>>>  >> <paul@...pouillou.net>
>>>  >>  > >>wrote:
>>>  >>  > >>>
>>>  >>  > >>>From: Maarten ter Huurne <maarten@...ewalker.org>
>>>  >>  > >>>
>>>  >>  > >>>OST is the OS Timer, a 64-bit timer/counter with buffered
>>>  >> reading.
>>>  >>  > >>>
>>>  >>  > >>>SoCs before the JZ4770 had (if any) a 32-bit OST; the 
>>> JZ4770
>>>  >> and
>>>  >>  > >>>JZ4780 have a 64-bit OST.
>>>  >>  > >>>
>>>  >>  > >>>This driver will register both a clocksource and a 
>>> sched_clock
>>>  >> to the
>>>  >>  > >>>system.
>>>  >>  > >>>
>>>  >>  > >>>Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
>>>  >>  > >>>Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>>  >>  > >>>---
>>>  >>  > >>>
>>>  >>  > >>>Notes:
>>>  >>  > >>>      v5: New patch
>>>  >>  > >>>
>>>  >>  > >>>      v6: - Get rid of SoC IDs; pass pointer to
>>>  >> ingenic_ost_soc_info
>>>  >>  > >>>as
>>>  >>  > >>>            devicetree match data instead.
>>>  >>  > >>>          - Use device_get_match_data() instead of the 
>>> of_*
>>>  >> variant
>>>  >>  > >>>          - Handle error of dev_get_regmap() properly
>>>  >>  > >>>
>>>  >>  > >>>      v7: Fix section mismatch by using
>>>  >>  > >>>builtin_platform_driver_probe()
>>>  >>  > >>>
>>>  >>  > >>>      v8: builtin_platform_driver_probe() does not work
>>>  >> anymore in
>>>  >>  > >>>          4.20-rc6? The probe function won't be called. 
>>> Work
>>>  >> around
>>>  >>  > >>>this
>>>  >>  > >>>          for now by using late_initcall.
>>>  >>  > >>>
>>>  >>  > >
>>>  >>  > >Did anyone notice this ? Either something is wrong with the
>>>  >> driver, or
>>>  >>  > >with the kernel core. Hacking around it seems like the worst
>>>  >> possible
>>>  >>  > >"solution".
>>>  >>  >
>>>  >>  > I can confirm it still happens on 5.0-rc3.
>>>  >>  >
>>>  >>  > Just to explain what I'm doing:
>>>  >>  >
>>>  >>  > My ingenic-timer driver probes with 
>>> builtin_platform_driver_probe
>>>  >> (this
>>>  >>  > works),
>>>  >>  > and then calls of_platform_populate to probe its children. 
>>> This
>>>  >> driver,
>>>  >>  > ingenic-ost, is one of them, and will fail to probe with
>>>  >>  > builtin_platform_driver_probe.
>>>  >>  >
>>>  >>
>>>  >>  The big question is _why_ it fails to probe.
>>>  >>
>>>  >
>>>  > Are you sharing the device tree node between a 'normal' platform
>>>  > device
>>>  > driver and something more low level DT that marks the device's 
>>> backing
>>>  > DT node as OF_POPULATED early on? That's my only guess why it's 
>>> not
>>>  > working.
>>> 
>>>  I do, but I clear the OF_POPULATED flag so that it is then probed 
>>> as a
>>>  normal platform device, and it's not on this driver's node but its
>>>  parent.
>>> 
>> 
>> Where do you clear the OF_POPULATED flag?
>> 
> 
> In the ingenic-timer driver introduced in patch [04/26], inside the 
> probe function.

Anything new on this? It still happens on 5.0-rc7.
It probes with late_initcall, and not with device_initcall.
I have no clue what's going on.

-Paul