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

[Cristian Ciocaltea <cristian.ciocaltea@collabora.com>]

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,
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