ipa: rpi: pisp: Add decompand support using PiSP hardware block #284
Conversation
This patch integrates a new decompand algorithm that utilizes the PiSP hardware block available on Raspberry Pi 5. The implementation enables conversion of companded sensor data into linear format prior to ISP processing. Changes include: - Implementation of decompand logic for controller and pipe interfaces - Enabling decompand block by "rpi.decompand" in tuning.json Signed-off-by: Sena Asotani <[email protected]>
|
Adding @njhollinghurst and @davidplowman for visilbity. @asofam thank you for this work! We would be happy to include this functionality into the IPA after review. |
src/ipa/rpi/pisp/pisp.cpp
Outdated
| return; | ||
|
|
||
| pisp_fe_decompand_config config = {}; | ||
| config.pad = decompandStatus->pad; |
There was a problem hiding this comment.
I would remove the pad field everywhere (except the existing config structure).
Our convention is to set padding/reserved fields to zero. The {} initializer will zero it here, which is all that's needed. fe->SetDecompand() will also replace it with zero.
I don't think we need any such field to exist in the tuning file or the metadata.
There was a problem hiding this comment.
P.S. if you use it for some other purpose, e.g. as a validity flag, please give it a different name!
There was a problem hiding this comment.
Thank you for the review! I've removed the pad field from the tuning file, status structure, and controller code as suggested. The PiSP config structure still retains the field, but it's now zero-initialized using {}.
This patch removes it from the tuning file, DecompandStatus, and related code. As per reviewer feedback, the 'pad' field is unnecessary outside the PiSP hardware config structure. Signed-off-by: Sena Asotani <[email protected]>
| void Decompand::initialValues(uint16_t LUT[]) | ||
| { | ||
| for (size_t i = 0; i < sizeof(decompandLUT_) / sizeof(decompandLUT_[0]); ++i) | ||
| { |
There was a problem hiding this comment.
There are a few formatting issues like this that will need to be fixed up before we can merge. There is a handy git commit hook that can be setup to run a check and give you the formatting errors. You can find more details here.
There was a problem hiding this comment.
Thank you for pointing that out. I wasn't aware of such a helpful tool!
I've run checkstyle.py and corrected the formatting issues accordingly.
| 29696, 31744, 33792, 35840, 37888, 39936, 41984, 44032, | ||
| 46080, 48128, 50176, 52224, 54272, 56320, 58368, 60416, | ||
| 62464 | ||
| ] |
There was a problem hiding this comment.
With the "gamma" tuning block, we specify a PWL instead of the hardware LUT. This is easier for users to visualize, manipulate, and tune for. The IPA (pisp.cpp) translates the PWL into the HW LUT needed to be programmed into the registers.
It would be nice if we can do the same with the decompand block as well - and it provides all the advantages of using PWLs instead of hardware specified LUTs. Would it be possible for you to make this change? Sorry, this is more work for you, but I think it will be better in the long run. Feel free to ask questions if things are unclear!
There was a problem hiding this comment.
Thank you for the suggestion!
I will give it a try to switch the decompand block to use a PWL instead of a hardware LUT, following the approach used in the gamma block. It may take a bit of time, but I will look into the gamma implementation and work from there.
If I run into any unclear points along the way, I would appreciate your guidance. Thank you again!
Adjusted indentation and formatting to comply with project style guidelines,as reported by checkstyle.py. Signed-off-by: Sena Asotani <[email protected]>
Summary
This pull request adds support for decompanding sensor data encoded with companding, using the PiSP hardware block
available on Raspberry Pi 5. The decompand operation is applied prior to ISP processing, enabling linearization of pixel values early in the pipeline.
Changes
1. Decompanding Algorithm
decompand_algorithm.h(interface)decompand.cpp/h(implementation)ipa/rpi/controller/.2. PiSP Hardware Support
pisp.cppwas modified to enable and configure this block based on the provided tuning parameters.3. Sensor Tuning Configuration
"rpi.decompand"parameters, includinglutandpadimx585.jsontuning file is derived from a version provided by soho-enterprise.co, with modifications limited to the"rpi.decompand"section.It may be updated or replaced in the future as upstream sensor support becomes available.
4. Architecture Consideration
Rationale
Decompanding is a critical early-stage operation in many modern image pipelines,
especially for sensors that output companded pixel values. By enabling this in the PiSP,
we offload the processing to dedicated hardware, improve performance, and lay the foundation
for accurate linear-space ISP tuning.
Notes
"rpi.decompand"key is defined.which is not part of the upstream Linux kernel or libcamera.
Testing
"rpi.decompand"configurationSigned-off-by
Signed-off-by: Sena Asotani [email protected]