Re: [PATCH v4 1/3] media: dt-bindings: rockchip,vdec: Add alternative reg-names order for RK35{76,88}

[Krzysztof Kozlowski <krzk@kernel.org>]

On 27/02/2026 18:42, Cristian Ciocaltea wrote:
> On 2/27/26 7:13 PM, Conor Dooley wrote:
>> On Fri, Feb 27, 2026 at 01:37:17PM +0200, Cristian Ciocaltea wrote:
>>> Hi Krzysztof, Conor,
>>>
>>> On 2/27/26 9:46 AM, Krzysztof Kozlowski wrote:
>>>> On Thu, Feb 26, 2026 at 12:46:53PM +0200, Cristian Ciocaltea wrote:
>>>>> With the introduction of the RK3588 SoC, and RK3576 afterwards, two more
>>>>> register blocks have been provided for the video decoder unit.
>>>>>
>>>>> However, the binding does not properly describe the new hardware layout,
>>>>
>>>> As you shown me last time with excerpt of address spaces from
>>>> datasheet/manual, the binding correctly describes the hardware and above
>>>> sentence is not true.
>>>>
>>>>> as it breaks the convention expecting the unit address to indicate the
>>>>> start of the first register range, i.e. 'function' block is listed
>>>>
>>>> Imprecise wording. "start of the main or primary register range"
>>>>
>>>> (if you have 0x1000 with one reg and 0x20000000 with everything, the
>>>> unit address will be 0x20000000).
>>>>
>>>>> before 'link' instead of the opposite.
>>>>>
>>>>> Since the binding changes have been already released and a fix would
>>>>> bring up an ABI break, mark the current 'reg-names' ordering as
>>>>> deprecated and introduce an alternative 'link,function,cache' listing
>>>>> which follows the address-based ordering according to the TRM.
>>>>>
>>>>> Additionally, drop the 'reg' description items as the order is not fixed
>>>>> anymore, while the information they offer is not very relevant anyway.
>>>>
>>>> This is fine for me.
>>>
>>> Thanks for the additional feedback!
>>>
>>> If I'm not mistaken (please correct me), the only remaining (hard)
>>> blocker for the series would be to improve this commit message.
>>
>> No, you also need to fix the problem I pointed out about reg-names being
>> optional on the devices you're relying on reg-names for. 
> 
> My only concern is that by marking reg-names as required we would break the ABI,

You are ALREADY BREAKING the ABI. Really, for absolutely non-important
cosmetic change in unit address, where I asked you repeatedly to fix the
unit address, you change the ABI affecting kernel and DTS users.

This is barely acceptable, but I am just annoyed already explain it to
you multiple times.

But now you claim, you can break ABI for cosmetic unimportant change,
but actually doing something meaningful is a no-go?

At least use correct arguments if you want to discuss.

> since the RK3588 related changes in the binding (not the DTS ones) got already
> released (i.e. since v6.17). That's also the reason we went with this deprecated
> order approach.
> 
>> The new commit
>> message I am happy with, provided you also add the information Nicolas
>> provided about the impact on users.
> 
> Nicolas, can you please provide here the statement so that we can agree on the
> wording?
> 
> Thanks,
> Cristian
> 
>>
>>>
>>> How about the following:
>>>
>>>     With the introduction of the RK3588 SoC, and RK3576 afterwards, three
>>>     register blocks have been provided for the video decoder unit instead of
>>>     just one, which are further referenced in the datasheet by 'link table',
>>>     'function' and 'cache'.  The former is present at the top of the
>>>     listing, starting at video decoder unit base address.
>>>
>>>     However, while documenting RK3588, the binding broke the convention
>>>     expecting the unit address to indicate the start of the primary register
>>>     range, i.e. the 'function' block got listed before the 'link' one.
>>>
>>>     Since the binding changes have been already released and a fix would
>>>     bring up an ABI break, mark the current 'reg-names' ordering as
>>>     deprecated and introduce an alternative 'link,function,cache' listing
>>>     which follows the address-based ordering according to the TRM.
>>>
>>>     Additionally, drop the 'reg' description items as the order is not fixed
>>>     anymore, while the information they offer is not very relevant anyway.
>>>
>>> Regards,
>>> Cristian
> 


Best regards,
Krzysztof