Re: [PATCH 0/9] Add Reset Controller support for Actions Semi Owl SoCs

Philipp Zabel
2018-07-30T15:38:50Z

On Mon, 2018-07-30 at 20:41 +0530, Manivannan Sadhasivam wrote:
> Hi Andreas,
>
> On Mon, Jul 30, 2018 at 12:26:07PM +0200, Andreas Färber wrote:
> > Hi Mani,
> >
> > Am 27.07.2018 um 20:45 schrieb Manivannan Sadhasivam:
> > > This patchset adds Reset Controller (RMU) support for Actions Semi
> > > Owl SoCs, S900 and S700. For the Owl SoCs, RMU has been integrated into
> > > the clock subsystem in hardware. Hence, in software we integrate RMU
> > > support into common clock driver inorder to maintain compatibility.
> >
> > Can this not be placed into drivers/reset/ by using mfd-simple with a
> > sub-node in DT?
> >
>
> Actually I was not sure where to place this reset controller driver. When I
> looked into other similar ones such as sunxi, they just integrated into the
> clk subsystem. So I just chose that path. But yeah, this is hacky!
>
> But this RMU is not MFD by any means. Since the CMU (Clock) and RMU (Reset)
> are two separate IPs inside SoC, we shouldn't describe it as a MFD driver. Since
> RMU has only 2 registers, the HW designers decided to use up the CMU memory
> map. So, maybe syscon would be best option I think. What is your opinion?

Using syscon seems cleaner than stuffing the regmap into owl_clk_desc.

> Even if we go for syscon, we should place the reset driver within clk
> framework as I can see other SoCs like Mediatek are doing the same. But again
> I'm not sure!

Me neither. If the CMU and RMU are really separate and only share the
memory map, a syscon driver could live in drivers/reset without
problems.
It's only when there are interactions between clocks and resets that you
really want to have the reset driver integrated with clk.

regards
Philipp