Re: [PATCH v4 0/5] Add Qualcomm JPEG V4L2 encoder for SM8250

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 7/10/26 2:28 PM, Dmitry Baryshkov wrote:
> On Thu, Jul 09, 2026 at 08:16:21PM +0200, Konrad Dybcio wrote:
>> On 7/9/26 9:33 AM, Dmitry Baryshkov wrote:
>>> On Wed, Jul 08, 2026 at 10:21:43PM +0100, Bryan O'Donoghue wrote:
>>>> On 08/07/2026 13:19, Konrad Dybcio wrote:
>>>>> On 7/7/26 12:41 PM, Bryan O'Donoghue wrote:
>>>>>> On 07/07/2026 11:11, Konrad Dybcio wrote:
>>>>>>> On 7/7/26 12:00 PM, Bryan O'Donoghue wrote:
>>>>>>>> On 07/07/2026 10:24, Konrad Dybcio wrote:
>>>>>>>>> On 7/6/26 3:37 PM, Bryan O'Donoghue wrote:
>>>>>>>>>> On 06/07/2026 14:02, Vladimir Zapolskiy wrote:

[...]

>>> Which way of representing device nodes makes it easier to migrate
>>> existing platform to the CSI PHY driver, while keeping compatibility
>>> with old DTs (yeah, ABI, old DTs must continue to work)?
>>
>> Quite frankly, I don't consider the existing (meganode) description
>> any valid, and would vote to rip it the second a replacement is
>> available. But once, not N times.
> 
> Rip without providing backwards compatibility?

Because the existing bindings make ensuring the required performance
state of power domains impossible, yes

> One of the options would be to follow the 'venus/iris' approach: land
> new set of component drivers, which target new platforms and provide
> minimal support for one old platform (maybe via autoapplied DT overlay
> or other similar techniques). Then continue migrating and phasing out
> camss driver for old platforms, while adding support for new blocks in
> the new set of drivers and ripping support from the camss driver after
> some migration time.
> 
>> This is not to blame any of the original implementers, this might
>> have seemed like the right idea for the tiny subsystem on msm8916.
> 
> Maybe...

Interestingly, there's a number more peirpherals inside the 8916
CAMSS too, I suppose some enthusiasts may poke at that one day,
there was quite a sizeable developer base for that SoC at one
point.

$ rg @ arch/arm64/boot/dts/qcom/msm8916-camera.dtsi
15:     qcom,msm-cam@1800000{
19:     qcom,csiphy@1b0ac00 {
41:     qcom,csiphy@1b0b000 {
63:     qcom,csid@1b08000  {
87:     qcom,csid@1b08400 {
111:    qcom,ispif@1b0a000 {
155:    qcom,vfe@1b10000 {
212:    qcom,jpeg@1b1c000 {
232:    qcom,irqrouter@1b00000 {
239:    qcom,cpp@1b04000 {
273:    cci: qcom,cci@1b0c000 {

(there's probably more hidden in magic reg accesses)

Konrad