Re: [PATCH 1/3] dt-bindings: bus: simple-pm-bus: Make clocks and power-domains optional

From: Tony Lindgren <tony@atomide.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	"open list:TI ETHERNET SWITCH DRIVER (CPSW)" 
	<linux-omap@vger.kernel.org>, Rob Herring <robh@kernel.org>,
	Simon Horman <horms+renesas@verge.net.au>,
	Suman Anna <s-anna@ti.com>
Subject: Re: [PATCH 1/3] dt-bindings: bus: simple-pm-bus: Make clocks and power-domains optional
Date: Thu, 7 Oct 2021 21:17:16 +0300	[thread overview]
Message-ID: <YV85rKlB79nMC+nq@atomide.com> (raw)
In-Reply-To: <CAMuHMdUzL7PWrUaO3CeCz7XXm=cmSg4BEZo582cxeTL_YuuETQ@mail.gmail.com>

* Geert Uytterhoeven <geert@linux-m68k.org> [211007 17:57]:
> Hi Tony,
> 
> On Thu, Oct 7, 2021 at 7:24 PM Tony Lindgren <tony@atomide.com> wrote:
> > * Geert Uytterhoeven <geert@linux-m68k.org> [211007 13:27]:
> > > On Thu, Oct 7, 2021 at 2:49 PM Tony Lindgren <tony@atomide.com> wrote:
> > > > Even without clocks and power domains configured, simple-pm-bus is still
> > > > different from simple-bus as simple-pm-bus enables runtime PM for the bus
> > > > driver.
> > >
> > > Which you need to have working Runtime PM for child devices, right? ;-)
> >
> > Right. And based on what I remember we simply cannot do pm_runtime_enable()
> > for simple-bus without breaking tons of devices.
> 
> Why not? Do you have an example of what would break?
> The only reason I created simple-pm-bus was because the DT people
> objected to adding PM to simple-bus, as they considered it wrong
> conceptually.  AFAIK this wouldn't have caused any actual breakage.

Oh OK, then I just remember the reasons wrong for the need for
adding it as a driver.

Regards,

Tony