linux-kernel - Re: [PATCH 17/22] mfd: sun6i-prcm: Add support for Allwinner A23 PRCM

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Date:	Tue, 27 May 2014 10:30:21 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Emilio Lopez <emilio@...pez.com.ar>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-serial@...r.kernel.org,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	devicetree <devicetree@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Luc Verhaegen <libv@...net.be>
Subject: Re: [PATCH 17/22] mfd: sun6i-prcm: Add support for Allwinner A23 PRCM

On Mon, May 26, 2014 at 12:36:38PM +0800, Chen-Yu Tsai wrote:
> On Mon, May 26, 2014 at 3:14 AM, Maxime Ripard
> <maxime.ripard@...e-electrons.com> wrote:
> > On Fri, May 23, 2014 at 03:51:20PM +0800, Chen-Yu Tsai wrote:
> >> The Allwinner A23 SoC has a PRCM unit like the previous A31 SoC.
> >> The differences are the AR100 clock can no longer be modified,
> >> and the APB0 clock has different divisors.
> >>
> >> This patch adds a compatible with a modified subdevice list for
> >> the A23.
> >>
> >> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
> >> ---
> >>  .../devicetree/bindings/mfd/sun6i-prcm.txt         |  2 +-
> >>  drivers/mfd/sun6i-prcm.c                           | 30 ++++++++++++++++++++++
> >>  2 files changed, 31 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/mfd/sun6i-prcm.txt b/Documentation/devicetree/bindings/mfd/sun6i-prcm.txt
> >> index 1f5a31f..03c5a55 100644
> >> --- a/Documentation/devicetree/bindings/mfd/sun6i-prcm.txt
> >> +++ b/Documentation/devicetree/bindings/mfd/sun6i-prcm.txt
> >> @@ -4,7 +4,7 @@ PRCM is an MFD device exposing several Power Management related devices
> >>  (like clks and reset controllers).
> >>
> >>  Required properties:
> >> - - compatible: "allwinner,sun6i-a31-prcm"
> >> + - compatible: "allwinner,sun6i-a31-prcm" or "allwinner,sun8i-a23-prcm"
> >>   - reg: The PRCM registers range
> >>
> >>  The prcm node may contain several subdevices definitions:
> >> diff --git a/drivers/mfd/sun6i-prcm.c b/drivers/mfd/sun6i-prcm.c
> >> index 718fc4d..c96bb6c 100644
> >> --- a/drivers/mfd/sun6i-prcm.c
> >> +++ b/drivers/mfd/sun6i-prcm.c
> >> @@ -76,16 +76,46 @@ static const struct mfd_cell sun6i_a31_prcm_subdevs[] = {
> >>       },
> >>  };
> >>
> >> +static const struct mfd_cell sun8i_a23_prcm_subdevs[] = {
> >> +     {
> >> +             .name = "sun6i-a31-apb0-clk",
> >> +             .of_compatible = "allwinner,sun8i-a23-apb0-clk",
> >> +             .num_resources = ARRAY_SIZE(sun6i_a31_apb0_clk_res),
> >> +             .resources = sun6i_a31_apb0_clk_res,
> >> +     },
> >> +     {
> >> +             .name = "sun6i-a31-apb0-gates-clk",
> >> +             .of_compatible = "allwinner,sun6i-a31-apb0-gates-clk",
> >> +             .num_resources = ARRAY_SIZE(sun6i_a31_apb0_gates_clk_res),
> >> +             .resources = sun6i_a31_apb0_gates_clk_res,
> >> +     },
> >
> > Did I just have a brainfart, or didn't you just introduced an
> > sun8i-a23-apb0-gates-clk driver?
> 
> My bad, I missed this one. The one in the DT is correct.
> It actually works, so I'm a bit confused here.
> Which one does the driver core actually use?

Actually, it will use both, and will match the of_compatible string
try to match it against the mfd-sub-nodes compatibles. If nothing
matches, it won't fill the dev.of_node field.

> 
> > And there's no ar100 and ahb0 clocks ?
> 
> The ahb0 is a fixed-factor (1:1) clock. There are no controls for it.
> The ar100 clock on the A23 has no controls either, so fixed-factor
> clock again.

Ack.

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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