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

[Paul Cercueil]

Le jeu. 24 janv. 2019 à 16:28, Stephen Boyd <sboyd@xxxxxxxxxx> 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@xxxxxxxxxxxx> a écrit :
> >  > >On 1/23/19 4:58 AM, Mathieu Malaterre wrote:
> >  > >>On Wed, Dec 12, 2018 at 11:09 PM Paul Cercueil 
> > <paul@xxxxxxxxxxxxxxx>
> >  > >>wrote:
> >  > >>>
> >  > >>>From: Maarten ter Huurne <maarten@xxxxxxxxxxxxxx>
> >  > >>>
> >  > >>>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@xxxxxxxxxxxxxx>
> >  > >>>Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  > >>>---
> >  > >>>
> >  > >>>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.