Re: [PATCH V2 2/2] reset: brcm-pmb: add driver for Broadcom's PMB

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Florian,

On Tue, 2020-12-08 at 12:20 -0800, Florian Fainelli wrote:
> On 12/8/20 3:02 AM, Philipp Zabel wrote:
> > Hi Rafał,
> > 
> > On Thu, 2020-11-19 at 13:56 +0100, Rafał Miłecki wrote:
> > > From: Rafał Miłecki <rafal@milecki.pl>
> > > 
> > > PMB can be found on BCM4908 and many other chipsets (e.g. BCM63138).
> > > It's needed to power on and off SoC blocks like PCIe, SATA, USB.
> > 
> > This sentence, the register names, and
> > the brcm_pmb_power_on/off_device/zone functions below make me worry that
> > this should be a power domain controller (pm_genpd in drivers/soc)
> > instead.
> > Does PM in PMB stand for power management by chance?
> 
> It does, PMB stands for Power Management Bus.
> 
> > If this actually cuts power to the USB and PCIe cores instead of just
> > controlling reset lines, it would be better to implement this
> > differently.
> 
> What is tricky is this is a combined reset/clock/power zones controller.
> You rarely turn off/assert one of those without also turning
> off/asserting the others.

It is common to have power management controllers also control clocks
and resets.
If the PMB controlled clocks and resets are only required for the power
on/off sequences, you should be able to move the current .(de)assert
implementations into a generic_pm_domain's .power_on and .power_off
methods.

regards
Philipp