Re: [PATCH 17/22] mfd: sun6i-prcm: Add support for Allwinner A23 PRCM - Chen-Yu Tsai

From: Chen-Yu Tsai <wens@csie.org>
To: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Lee Jones <lee.jones@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mike Turquette <mturquette@linaro.org>,
	Emilio Lopez <emilio@elopez.com.ar>,
	Linus Walleij <linus.walleij@linaro.org>,
	linux-serial@vger.kernel.org,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	devicetree <devicetree@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Boris BREZILLON <boris.brezillon@free-electrons.com>,
	Luc Verhaegen <libv@skynet.be>
Subject: Re: [PATCH 17/22] mfd: sun6i-prcm: Add support for Allwinner A23 PRCM
Date: Thu, 29 May 2014 12:23:58 +0800	[thread overview]
Message-ID: <CAGb2v65v7rqBwFbn1JtQv44nQxepAq-ciwsBdHaELbzWXQNU9g@mail.gmail.com> (raw)
In-Reply-To: <20140527083021.GE4730@lukather>

On Tue, May 27, 2014 at 4:30 PM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> 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@free-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@csie.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.

So actually it was supposed to use "allwinner,sun6i-a31-apb0-gates-clk",
as that clk driver takes clock-indices, so no need to define gate masks
and tie them to some new compatible.

There was no sun8i-a23-apb0-gates-clk driver.

I must not be getting enough sleep.

>> > 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