Hi Geert-san,
> From: Geert Uytterhoeven
> Sent: Wednesday, July 5, 2017 9:22 PM
>
> Hi Shimoda-san,
>
> On Wed, Jul 5, 2017 at 1:57 PM, Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> >> From: Geert Uytterhoeven
> >> Sent: Wednesday, July 5, 2017 7:09 PM
> >> On Wed, Jun 28, 2017 at 8:28 AM, Yoshihiro Shimoda
> >> <yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> >> > R-Car USB 2.0 controller can change the clock source from an oscillator
> >> > to an external clock via a register. So, this patch adds support
> >> > the clock source selector as a clock driver.
>
> >> > --- /dev/null
> >> > +++ b/drivers/clk/renesas/rcar-usb2-clock-sel.c
>
> >> > +/* Since this driver needs other ccf drivers, this uses subsys_initcall_sync */
> >> > +subsys_initcall_sync(rcar_usb2_clock_sel_init);
> >>
> >> I suppose this is a workaround for the lack of probe deferral support in the
> >> USB subsystem?
> >
> > This is my fault. I added "power-domains" property into this device's node.
> > After I remove the power-domains like the cpg node, this driver can use subsys_initcall()
> > instead of subsys_initcall_sync().
>
> Does the clock sel module requires the functional clock "ehci_ohci" to be
> running before you can access its registers?
> If yes, I think there should be a "power-domains" property.
Yes. But...
> Then, you can simplify the code by calling
>
> pm_runtime_enable(dev);
> pm_runtime_get_sync(dev);
>
> and remove the explicit handling of the functional clock.
>
> That does not solve probe deferral handling in the USB subsystem, though.
I added a debug message at end of cpg_mssr_probe(), and if I used subsys_initcall() on
rcar-usb2-clock-sel driver, kernel log output below:
========================
[ 0.272547] rcar-usb2-clock-sel e6590630.clock-controller: probe deferral not supported
[ 0.273944] ----------------- cpg_mssr_probe: probed!
========================
So, it seems the renesas-cpg-mssr.c doesn't solve probe deferral handling.
(The driver renesas-cpg-mssr.c uses platform_driver_probe() for now.)
So, IIUC, this rcar-usb2-clock-sel driver cannot use subsys_initcall().
Or, should we modify the renesas-cpg-mssr.c somehow?
Best regards,
Yoshihiro Shimoda
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> 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
