Re: [PATCH v12 3/3] dt-bindings: mfd: Document Renesas R-Car Gen3 RPC-IF MFD bindings

From: masonccyang@mxic.com.tw
To: "Geert Uytterhoeven" <geert@linux-m68k.org>
Cc: "Boris Brezillon" <bbrezillon@kernel.org>,
	"Mark Brown" <broonie@kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Simon Horman" <horms@verge.net.au>,
	juliensu@mxic.com.tw, "Lee Jones" <lee.jones@linaro.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Linux-Renesas" <linux-renesas-soc@vger.kernel.org>,
	"linux-spi" <linux-spi@vger.kernel.org>,
	"Marek Vasut" <marek.vasut@gmail.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Rob Herring" <robh@kernel.org>,
	"Sergei Shtylyov" <sergei.shtylyov@cogentembedded.com>,
	zhengxunli@mxic.com.tw
Subject: Re: [PATCH v12 3/3] dt-bindings: mfd: Document Renesas R-Car Gen3 RPC-IF MFD bindings
Date: Tue, 21 May 2019 09:28:35 +0800	[thread overview]
Message-ID: <OF6A21896F.72833899-ON48258401.0007B494-48258401.00081C05@mxic.com.tw> (raw)
In-Reply-To: <CAMuHMdU5a2qXVG52Creftp4wR_nnwB9xk=jFeiOWUO0vJSyV0w@mail.gmail.com>

Hi Geert,

> 
> On Mon, May 20, 2019 at 9:24 AM <masonccyang@mxic.com.tw> wrote:
> > > >>>   - clocks: should contain 1 entries for the module's clock
> > > >>>   - clock-names: should contain "rpc"
> > > >>
> > > >>    I suspect we'd need the RPC/RPCD2 clocks mentioned as well 
(not
> > sure
> > > > yet)...
> > > >
> > > > Need it ?
> > >
> > >    You seem to call clk_get_rate() on the module clock, I doubt 
that's
> > > correct topologically...
> >
> > I think it's correct but just like Geert mentioned that there is no 
any
> > patch
> > in drivers/clk/renesas/r8a77995-cpg-mssr.c adding RPC-related clocks.
> >
> >
> > I patched dt-bindings/clock/r8a77995-cpg-mssr.h for some simple 
testing
> >
> > -#define R8A77995_CLK_RPC               29
> > -#define R8A77995_CLK_RPCD2             30
> > +#define R8A77995_CLK_RPC               31
> > +#define R8A77995_CLK_RPCD2             32
> 
> That change doesn't make sense to me...
> 
> > by clk_prepare_enable() & clk_disable_unprepare() with CPG_MOD 917
> > on D3 draak board, it is working fine.
> 
> ... and is not sufficient to allow the above two calls.
> 
> Besides, making explicit clk_prepare_enable() calls bypasses Runtime PM
> and the automatic disabling of unused clocks, thus hiding bugs related 
to
> Runtime PM.  Which is probably why your driver doesn't work for 
Sergei...
> 

Got it, thanks for your explanation.

best regards,
Mason

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