Re: [PATCH v3] ARM: dts: Add gyro and accel to APQ8060 Dragonboard

From: Linus Walleij <linus.walleij@linaro.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Quan Nguyen <qnguyen@apm.com>
Cc: Ivan Ivanov <iivanov.xz@gmail.com>,
	Andy Gross <andy.gross@linaro.org>,
	"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
	Stephen Boyd <sboyd@codeaurora.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	David Brown <david.brown@linaro.org>
Subject: Re: [PATCH v3] ARM: dts: Add gyro and accel to APQ8060 Dragonboard
Date: Thu, 3 Nov 2016 09:46:03 +0100	[thread overview]
Message-ID: <CACRpkdbRXXH=gadxfuK7J+FTvN=oaLRt+-WB5pQ8rDsK1BGXpA@mail.gmail.com> (raw)
In-Reply-To: <20161101231708.GM25787@tuxbot>

[CC Quan who made a nice hierarchical domain]

On Wed, Nov 2, 2016 at 12:17 AM, Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
> On Tue 01 Nov 04:31 PDT 2016, Linus Walleij wrote:
>
>> On Mon, Oct 31, 2016 at 11:20 PM, Bjorn Andersson
>> <bjorn.andersson@linaro.org> wrote:
>>
>> >> +                                     interrupt-parent = <&pm8058_gpio>;
>> >> +                                     interrupts = <208 IRQ_TYPE_EDGE_FALLING>;
>> >
>> > To remove the need of resetting the interrupt-parent in each child you
>> > can use the following form:
>> >
>> >     interrupts-extended = <&pm8058_gpio 208 IRQ_TYPE_EDGE_FALLING>;
>> >
>> > But, if we correct the ssbi gpio driver then this would no longer be
>> > interrupt 208 in this parent, right?. I believe that if you say
>> > <&pmicintc 208 IRQ_TYPE_EDGE_FALLING> instead, which should work even
>> > after we correct the gpio translation.
>>
>> Yes. It should be fixed everywhere but is not related to this
>> patch. But I can do a two-patch series first fixing this and then
>> adding the gyro+accelerometer on top referencing the MFD
>> pmicintc as parent.
>>
>
> Sorry, I'm not sure I'm following.
>
> What I tried to say was that before the correction of the GPIO block's
> window this particular IRQ would be #208 in &pmicintc and #208 in
> &pm8058_gpio. After the correction of the window the IRQ is #208 in
> &pmicintc and #17 in &pm8058_gpio.
>
> As such, using #208 from &pmicintc would make this work through the
> correction of the GPIO driver. Perhaps I'm wrong about this?

No that is exactly what I mean. I just mean I should not use
the pm8058_gpio as interrupt parent at all for now.

(You will see in my patch set, cooking it.)

>> What needs to happen is for the SSBI and SPMI GPIO to use a
>> hierarchical irqdomain so their GPIO local line offset and hwirq
>> are the same. Then we can reference the GPIO IRQ lines directly
>> in a correct manner.
>
> Right. Do you have any example of drivers getting this right? I did take
> a quick look but didn't find one.

It seems drivers/gpio/gpio-xgene-sb.c is doing something like
what we want. See for example how it picks out the parent domain
and hangs a new domain off it.

If possible, I would like to add infrastructure for this to gpiolib,
if it can be made generic and make sense.

Yours,
Linus Walleij