Re: [PATCH v2] clk: renesas: rcar-usb2-clock-sel: Add R-Car USB 2.0 clock selector PHY

Hi Shimoda-san,

On Wed, Jul 5, 2017 at 1:57 PM, Yoshihiro Shimoda
[off-list ref] wrote:

quoted

From: Geert Uytterhoeven
Sent: Wednesday, July 5, 2017 7:09 PM
On Wed, Jun 28, 2017 at 8:28 AM, Yoshihiro Shimoda
[off-list ref] wrote:

quoted

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.

quoted

quoted

--- /dev/null
+++ b/drivers/clk/renesas/rcar-usb2-clock-sel.c

quoted

quoted

+/* 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.

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.

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