Re: [PATCH 1/2] ARM: Rockchip: Handle rk3288/rk3288w revision

[Mylene Josserand <mylene.josserand@collabora.com>]

Hello everyone,

Thank you for all these feedback and discussion about my patches.

On 3/6/20 11:45 AM, Geert Uytterhoeven wrote:
> Hi Heiko,
> 
> On Wed, Mar 4, 2020 at 12:00 PM Heiko Stübner <heiko@sntech.de> wrote:
>> Am Montag, 2. März 2020, 16:57:02 CET schrieb Mylène Josserand:
>>> Determine which revision of rk3288 by checking the HDMI version.
>>> According to the Rockchip BSP kernel, on rk3288w, the HDMI
>>> revision equals 0x1A which is not the case for the rk3288 [1].
>>>
>>> As these SOC have some differences, the new function
>>> 'soc_is_rk3288w' will help us to know on which revision
>>> we are.
>>
>> what happened to just having a different compatible in the dts?
>> Aka doing a
>>
>> rk3288w.dtsi with
>>
>> #include "rk3288.dtsi"
>>
>> &cru {
>>          compatible = "rockchip,rk3288w-cru";
>> }
>>
>> I somehow don't expect boards to just switch between soc variants
>> on the fly.
>>
>> Also, doing things in mach-rockchip is not very future-proof:
>>
>> (1) having random soc-specific APIs spanning the kernel feels wrong,
>>      especially as at some point it might not be contained to our own special
>>      drivers like the cru. I cannot really see people being enthusiastic if
>>      something like this would be needed in say the core Analogix-DP bridge ;-)
> 
> Indeed.  You're better of registering an soc_device_attribute using
> soc_device_register(), after which any driver can use soc_device_match()
> to differentiate based on the SoC revision.

Thank you for this suggestion. The issue is that clocks are registered 
at an early stage of the boot so using initcalls is too late for the 
clock differentiation :(

> 
>> (2) I guess the rk3288w will not be the last soc doing this and on arm64 you
>>      can't do it that way, as there is no mach-rockchip there
> 
> There's drivers/soc/rockchip ;-)
> 
>> So my personal preference would really would be just a specific compatible
>> for affected ip blocks.
> 
> Doing that only for affected IP blocks may miss integration differences.
> Of course, you can always resort to soc_device_match() to handle those...
> 
> Gr{oetje,eeting}s,
> 
>                          Geert
> 

It would be a great idea indeed if there was not this clock registration 
too soon for initcalls.

I am currently running out of ideas to propose a better solution than 
this V1. Is anyone has any recommendation to handle that? I would really 
appreciate :)

Thank you in advance!
Best regards,
Mylène

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