Re: [PATCH] clk: hi6220: use CLK_OF_DECLARE_DRIVER for sysctrl and mediactrl clock init

[Shawn Guo <shawnguo@kernel.org>]

Hi John,

On Mon, Oct 10, 2016 at 10:39:12AM -0700, John Stultz wrote:
> On Sat, Oct 8, 2016 at 6:38 AM, Shawn Guo <shawn.guo@linaro.org> wrote:
> > The hi6220-sysctrl and hi6220-mediactrl are not only clock provider but
> > also reset controller.  It worked fine that single sysctrl/mediactrl
> > device node in DT can be used to initialize clock driver and populate
> > platform device for reset controller.  But it stops working after
> > commit 989eafd0b609 ("clk: core: Avoid double initialization of clocks")
> > gets merged.  The commit sets flag OF_POPULATED during clock
> > initialization to skip the platform device populating for the same
> > device node.  On hi6220, it effectively makes hi6220-sysctrl reset
> > driver not probe any more.
> >
> > The patch changes hi6220 sysctrl and mediactrl clock init macro from
> > CLK_OF_DECLARE to CLK_OF_DECLARE_DRIVER, so that the reset driver using
> > the same hardware block can continue working.
> >
> > Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> 
> Tested-by: John Stultz <john.stultz@linaro.org>
> 
> I hit this as well last week when 989eafd0b609 ("clk: core: Avoid
> double initialization of clocks") landed, which killed graphics on my
> HiKey.
> 
> My workaround was a bit hackish, as I don't really know when one
> should use OF_DECLARE vs OF_DECLARE_DRIVER, but I also converted the
> hi6220_clk_ao and hi6220_clk_power to the _DRIVER side. Your patch
> seems to work just as well for me, but I wanted to double check with
> you that the ao/power clks didn't need the conversion as well.

For now, clock driver is the only one matching compatible
"hisilicon,hi6220-aoctrl" and "hisilicon,hi6220-pmctrl".  Whoever
adding a platform driver probing the same compatible later will have
to change it CLK_OF_DECLARE_DRIVER.  Otherwise, the platform driver
simply doesn't probe.

Shawn