Date:	Wed, 09 Apr 2014 20:04:52 +0200
From:	Boris BREZILLON <boris.brezillon@...e-electrons.com>
To:	Chen-Yu Tsai <wens@...e.org>
CC:	Randy Dunlap <rdunlap@...radead.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Emilio López <emilio@...pez.com.ar>,
	Mike Turquette <mturquette@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	devicetree <devicetree@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH 00/15] ARM: sunxi: add A31 PL pins support


On 09/04/2014 19:14, Chen-Yu Tsai wrote:
> On Thu, Apr 10, 2014 at 12:14 AM, Boris BREZILLON
> <boris.brezillon@...e-electrons.com> wrote:
>> On 09/04/2014 16:53, Chen-Yu Tsai wrote:
>>> Hi Boris,
>>>
>>> On Wed, Apr 9, 2014 at 9:51 PM, Boris BREZILLON
>>> <boris.brezillon@...e-electrons.com> wrote:
>>>> Hello,
>>>>
>>>> This series rework the sunxi pinctrl driver to support the PLx pins
>>>> available on the A31 SoC.
>>> Thanks for working on this. I mentioned to Maxime on IRC yesterday that
>>> we have complete pinctrl drivers for both A31 and A23, based on our current
>>> pinctrl-sunxi driver, in the A23 SDK. These have the complete pin mapping.
>> Thanks for pointing this out, I'll take a look.
>>
>>>> It also add missing A31 reset controller DT bindings documentation.
>>>>
>>>> I need those PL pins (actually I only need PL0 and PL1) to support
>>>> the P2WI bus, which in turn is used to communicate with the AXP221
>>>> PMIC.
>>> If you could, please add all the PL and PM pins.
>> Sure, I'll add pin macros for L and M ports.
>>
>>> As I said, you can find complete definitions in the A23 SDK.
>>>
>>>> Let me know if these changes are too intrusive.
>>> I wonder if we should do a separate driver for the new PIO controller.
>>> Clearly it's a separate IP block, with it's own clock and reset controls.
>> This is what I had in mind in the first place, but then I encountered
>> several issues when doing so:
>>
>>  1) the gpio chip is not dynamically allocated but is declared as a
>> static variable instead
> Hmm. Not sure if this is worth the change.

We have to dynamically allocate the gpio chip struct, otherwise you
would add several times the same struct in the gpio_chips list (when you
call gpiochip_add), which will mess up the list.

Actually, I just realized a gpio chip struct was allocated (line 854)
but then the pointer to this chip was overridden with the address to the
static definitions (line 861):

http://lxr.free-electrons.com/source/drivers/pinctrl/pinctrl-sunxi.c#L854


>
>>  2) we have to tweak the pinctrl base field, otherwise the pin numbers
>> overlap
> Documentation says pin numbers are global, however the pinctrl core code
> only looks up a pin by number in a pinctrl device only.
>
> Also I see mfd pinctrl drivers (ab8500, as3722) have pin numbers starting
> from 0. So definitely some confusion there.

I was talking about the base field of the gpio_chip struct.
This field is used to give a unique gpio id from the GPIO point of view:
unique_gpio_id = gpio_id_within_the_gpio_chip + chip->base.

You can get an automatically assigned gpio base if you set it to -1
before calling gpiochip_add, but AFAIK (correct me if I'm wrong) this is
used for hotplugable GPIO chips.

For ARCH gpios you


>
>>  3) other things I haven't noticed yet :-)
> Reworking EINT to use one interrupt per bank will yield some more surprises.
>
> There's also new gpiolib irqchip helpers, but that will require reworking
> each pin bank into separate gpio chips. May be more work than just adding
> different irq domains for different banks.
>
> See: https://lkml.org/lkml/2014/3/25/175

Okay, I'll take a look.

>
>> I'll try to rework the driver to be able to declare 2 separated pin
>> controllers.
> Thanks again.
>
> ChenYu
>
>>> Allwinner sources list this block as "R_PIO". I suggest using this name.
>>> Clearly "pioL" does not cover all the functionality.
>> Fair enough. I'll modify it.
>>
>>> I have started to document the PRCM block: http://linux-sunxi.org/PRCM
>>>
>>> Last, please send the patches to the linux-sunxi mailing list as well.
>>> At the very least, Hans will see them and add them to sunxi-devel branch.
>> Sure, this is an oversight, I'm using get_maintainer and just forgot to
>> add Hans and the linux-sunxi ML. But I'll take care to add you, hans and
>> the sunxi ML in Cc next time.
>>
>> Thanks for your review.
>>
>> Best Regards,
>>
>> Boris
>>
>>>
>>> Cheers,
>>> ChenYu
>>>
>>>> Best Regards,
>>>>
>>>> Boris
>>>>
>>>> Boris BREZILLON (15):
>>>>   ARM: sunxi: dt: list all pinctrl compatible strings
>>>>   ARM: sunxi: dt: document pinctrl clock related properties
>>>>   ARM: sunxi: dt: add pinctrl clock-names properties
>>>>   pinctrl: sunxi: specify clk name when retrieving pinctrl pio clk
>>>>   clk: sunxi: add A31 APB0 clk gate defintions
>>>>   clk: sunxi: add A31 APB0 gates compatible string to the documentation
>>>>   ARM: sunxi: dt: define A31's APB0 clk gates node
>>>>   reset: sunxi: document sunxi's reset controllers bindings
>>>>   clk: sunxi: add A31 APB0 reset line defintions
>>>>   pinctrl: sunxi: add PL pin definitions
>>>>   pinctrl: sunxi: add support for A31 PL pins
>>>>   pinctrl: sunxi: retrieve and enable PL clk gate for A31 SoC
>>>>   pinctrl: sunxi: retrieve and enable PL reset line for A31 SoC
>>>>   pinctrl: sunxi: define A31 PL0/PL1 pins
>>>>   ARM: sunxi: dt: add support for A31's PL pins
>>>>
>>>>  Documentation/devicetree/bindings/clock/sunxi.txt  |   1 +
>>>>  .../bindings/pinctrl/allwinner,sunxi-pinctrl.txt   |  13 +-
>>>>  .../bindings/reset/allwinner,sunxi-clock-reset.txt |  21 +++
>>>>  arch/arm/boot/dts/sun4i-a10.dtsi                   |   1 +
>>>>  arch/arm/boot/dts/sun5i-a10s.dtsi                  |   1 +
>>>>  arch/arm/boot/dts/sun5i-a13.dtsi                   |   1 +
>>>>  arch/arm/boot/dts/sun6i-a31.dtsi                   |  25 ++-
>>>>  arch/arm/boot/dts/sun7i-a20.dtsi                   |   1 +
>>>>  drivers/clk/sunxi/clk-sunxi.c                      |   5 +
>>>>  drivers/pinctrl/pinctrl-sunxi-pins.h               |   8 +
>>>>  drivers/pinctrl/pinctrl-sunxi.c                    | 205 +++++++++++++++------
>>>>  drivers/pinctrl/pinctrl-sunxi.h                    |  39 +++-
>>>>  12 files changed, 264 insertions(+), 57 deletions(-)
>>>>  create mode 100644 Documentation/devicetree/bindings/reset/allwinner,sunxi-clock-reset.txt
>>>>
>>>> --
>>>> 1.8.3.2
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> linux-arm-kernel@...ts.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>> --
>> Boris Brezillon, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com
>>

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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