linux-kernel - Re: [RFC PATCH 0/3] ARm64: amlogic: Introduce common GX family dtsi

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Message-ID: <7hh9a068f9.fsf@baylibre.com>
Date:   Wed, 31 Aug 2016 12:32:42 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     Andreas Färber <afaerber@...e.de>,
        Carlo Caione <carlo@...one.org>,
        devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-amlogic <linux-amlogic@...ts.infradead.org>
Subject: Re: [RFC PATCH 0/3] ARm64: amlogic: Introduce common GX family dtsi

Neil Armstrong <narmstrong@...libre.com> writes:

> On 08/29/2016 10:15 PM, Andreas Färber wrote:
>> Am 29.08.2016 um 21:50 schrieb Carlo Caione:
>>> On 29/08/16 20:38, Andreas Färber wrote:
>>>> Am 29.08.2016 um 10:01 schrieb Carlo Caione:
>>>>> On Mon, Aug 29, 2016 at 9:56 AM, Neil Armstrong <narmstrong@...libre.com> wrote:
>>>>>> Neil Armstrong (3):
>>>>>>   ARM64: dts: amlogic: Add Meson GX Family common dtsi
>>>>>>   ARM64: dts: amlogic: Switch Meson GXL dtsi to use common GX dtsi
>>>>>>   ARM64: dts: amlogic: Switch Meson GXBB dtsi to use common GX dtsi
>>>>
>>>> Adding an unused .dtsi duplicating GXBB makes me uneasy.
>>>
>>> S905x (GXL) is different from S905 (GXBB), it's unused now but in the
>>> future we can expect something different in the two DTSI.
>> 
>> Guess I need to be --verbose. ;)
>> 
>> I meant: After patch 1/3 there is a gx-common.dtsi that duplicates
>> contents of gxbb.dtsi and is not yet #include'd anywhere, i.e., unused.
>> 
>>>> Any chance we can simplify this to at most two steps?
>>>> 1) Move code from gxbb to gx (1/3 + 3/3)
>>>> 2) Add gxl using gx ("Add basic support for Amlogic S905X" + 2/3)
>>>
>>> fine by me.
>
> I can merge carlo's GXL support into this patchet.
>
>>>
>>>> Alternatively:
>>>> 1) "Add basic support for Amlogic S905X"
>>>> 2) Factor out common bits (1/3 + 2/3 + 3/3)
>>>
>>> how is this different from this patchset?
>> 
>> I'm suggesting we do "atomic" move operations, not copy and then remove.
>> 
>> The difference between my two suggestions is how many and which changes
>> we squash - I do appreciate that it's easy for review as is but what I
>> have in mind is that either we should get this refactoring applied asap
>> (#1 1)) and rebase all pending patches on it, or we may need to rebase
>> the refactoring onto any pending MMC, SDIO, etc. patches, which I feel
>> is safer to do in one big patch (#2 2)) than split over multiple ones.
>> It really depends on the merge order and roadmap you guys have in mind.
>
> I'm not very convinced about the utility the reduce commits... having a dtsi alone won't arm anyone.
> Nevertheless, I will squash the two commits.
>
>> 
>>>> As for bike-shedding, is there a GX family as well or could we drop
>>>> -common? .dtsi is always something common - compare Exynos or i.MX.
>>>> Since there are meson8b and meson8 I was anticipating that after gxbb
>>>> would come gx, not gxl.
>>>
>>> AFAIK we have:
>>> - GXBB
>>> - GXL
>>> - GXM
>>> - GXTVBB
>>>
>>>> Do you know what the L in GXL is for? Should we consider renaming gxbb
>>>> to gxb, and then also insert -s905 as suggested by Kevin, for symmetry?
>>>
>>> Yes, that make sense.
>
> As Amlogic told us, we have at least two families :
>  - GXBB with the S905
>  - GXL with the S905D and S905X
>
> The GXL and GXBB families will share a lot, except the clocks tree, pinctrl registers, USB IP versions and at least ethernet PHY handling.
>
> But the two GXL SoCs will still share a lot, maybe everything, we are not sure for now.
>
> In the Amlogic SDK kernel, we can see more families :
>  - GXM seems to be the S912 since it has two clusters of 4xA53, but looks identical to GXL for pinctrl and clocks
>  - GXTVBB looking at the Amlogic SDK it could be a GXBB variant with a different GPU (t83x instead of mali450), pinctrl and clocks
>
> In their SDK, there is a single GXL pinctrl and clock driver for GXL and GXM.
>
> Taking in account all the boards, families and SoCs, we should have the following:
> meson-gx-common.dtsi
> ├── meson-gxbb-s905.dtsi
> │   ├── meson-gxbb-s905-odroidc2.dts
> │   └── meson-gxbb-s905-p20x.dtsi
> │       ├── meson-gxbb-s905-p200.dts
> │       └── meson-gxbb-s905-p201.dts
> ├── meson-gxl.dtsi
> │   ├── meson-gxl-s905d.dtsi
> │   │   └── meson-gxl-s905d-p23x.dts
> │   │       ├── meson-gxl-s905d-p230.dts
> │   │       └── meson-gxl-s905d-p231.dts
> │   └── meson-gxl-s905x.dtsi
> │       └── meson-gxl-s905x-p212.dts
> └── meson-gxm-s912.dtsi
>     └── meson-gxm-s912-q20x.dtsi
>         ├── meson-gxm-s912-q200.dts
>         └── meson-gxm-s912-q201.dts
>
> But since GXBB will only be S905, we can drop the S905 naming and keep what is already upstream,
> then GXM won't happen until a certain time so I plan to push the following :
>
> meson-gx-common.dtsi

nit: drop the -common, as suggested by Andreas since it's kidna
redundant since it's a .dtsi.

> ├── meson-gxbb.dtsi
> │   ├── meson-gxbb-odroidc2.dts
> │   └── meson-gxbb-p20x.dtsi
> │       ├── meson-gxbb-p200.dts
> │       └── meson-gxbb-p201.dts
> └── meson-gxl.dtsi
>     ├── meson-gxl-s905d.dtsi
>     │   └── meson-gxl-s905d-p23x.dts
>     │       ├── meson-gxl-s905d-p230.dts
>     │       └── meson-gxl-s905d-p231.dts
>     └── meson-gxl-s905x.dtsi
>         └── meson-gxl-s905x-p212.dts
>
> But the meson-gxl-s905d.dtsi, meson-gxl-s905x.dtsi and meson-gxl.dtsi will be empty until we push the pinctrl, clock, ethernet PHY and USB nodes for them.

Looks good to me.

Kevin