[PATCH v3 3/4] libcamera: converter: Add DW100 converter class

[Umang Jain]

Hi Kieran,

On 26/06/24 2:26 am, Kieran Bingham wrote:
> Quoting Umang Jain (2024-06-25 07:23:26)
>> DW100 Dewarp engine is present on i.MX8MP SoC. This patch
>> provides a converter class (inherited from V4L2M2MConverter).
>>
>> The DW100 converter will be used for scaling capabilites hence, has
>> a helper to set scaler crop rectangles. Plumbing in the RkISP1
>> pipeline-handler is done in the subsequent patch.
>>
>> The ConverterDW100 class can be extended later (as additional
>> developement) to support the dewarping by setting a dewarp vertex map.
>>
>> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
>> ---
>>   .../internal/converter/converter_dw100.h      | 26 +++++++++
>>   .../libcamera/internal/converter/meson.build  |  1 +
>>   src/libcamera/converter/converter_dw100.cpp   | 56 +++++++++++++++++++
>>   src/libcamera/converter/meson.build           |  1 +
>>   4 files changed, 84 insertions(+)
>>   create mode 100644 include/libcamera/internal/converter/converter_dw100.h
>>   create mode 100644 src/libcamera/converter/converter_dw100.cpp
>>
>> diff --git a/include/libcamera/internal/converter/converter_dw100.h b/include/libcamera/internal/converter/converter_dw100.h
>> new file mode 100644
>> index 00000000..ae6d0732
>> --- /dev/null
>> +++ b/include/libcamera/internal/converter/converter_dw100.h
>> @@ -0,0 +1,26 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> +/*
>> + * Copyright (C) 2024, Ideas On Board Oy
>> + *
>> + *i.MX8MP Dewarp Engine integration
> s/*i.MX8MP/* i.MX8MP/
>
>> + */
>> +
>> +#pragma once
>> +
>> +#include "libcamera/internal/converter/converter_v4l2_m2m.h"
>> +
>> +namespace libcamera {
>> +
>> +class MediaDevice;
>> +class Rectangle;
>> +class Stream;
>> +
>> +class ConverterDW100 : public V4L2M2MConverter
>> +{
>> +public:
>> +       ConverterDW100(std::shared_ptr<MediaDevice> media);
>> +
>> +       int setScalerCrop(const Stream *stream, Rectangle rect);
>> +};
>> +
>> +} /* namespace libcamera */
>> diff --git a/include/libcamera/internal/converter/meson.build b/include/libcamera/internal/converter/meson.build
>> index 891e79e7..85007a4b 100644
>> --- a/include/libcamera/internal/converter/meson.build
>> +++ b/include/libcamera/internal/converter/meson.build
>> @@ -1,5 +1,6 @@
>>   # SPDX-License-Identifier: CC0-1.0
>>   
>>   libcamera_internal_headers += files([
>> +    'converter_dw100.h',
>>       'converter_v4l2_m2m.h',
>>   ])
>> diff --git a/src/libcamera/converter/converter_dw100.cpp b/src/libcamera/converter/converter_dw100.cpp
>> new file mode 100644
>> index 00000000..04e6942f
>> --- /dev/null
>> +++ b/src/libcamera/converter/converter_dw100.cpp
>> @@ -0,0 +1,56 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> +/*
>> + * Copyright (C) 2024, Ideas On Board Oy
>> + *
>> + * i.MX8MP Dewarp Engine integration
>> + */
>> +
>> +#include "libcamera/internal/converter/converter_dw100.h"
>> +
>> +#include <libcamera/base/log.h>
>> +
>> +#include <libcamera/geometry.h>
>> +
>> +#include "libcamera/internal/media_device.h"
>> +#include "libcamera/internal/v4l2_videodevice.h"
>> +
>> +namespace libcamera {
>> +
>> +LOG_DECLARE_CATEGORY(Converter)
>> +
>> +/**
>> + * \class libcamera::ConverterDW100
>> + * \brief The i.MX8MP dewarp converter implements the converter interface based
>> + * on V4L2 M2M device.
>> +*/
>> +
>> +/**
>> + * \fn ConverterDW100::ConverterDW100
>> + * \brief Construct a ConverterDW100 instance
>> + * \param[in] media The media device implementing the converter
>> + */
>> +ConverterDW100::ConverterDW100(std::shared_ptr<MediaDevice> media)
>> +       : V4L2M2MConverter(media.get())
>> +{
>> +}
>> +
>> +/**
>> + * \brief Set the scaler crop rectangle \a rect on \a stream
>> + * \param[in] stream Pointer to output stream
>> + * \param[inout] rect The selection rectangle to be applied
>> + *
>> + * \return 0 on success or a negative error code otherwise
>> + */
>> +int ConverterDW100::setScalerCrop(const Stream *stream, Rectangle rect)
>> +{
>> +       int ret;
>> +
>> +       ret = setSelection(stream, V4L2_SEL_TGT_CROP, &rect);
>> +       if (ret < 0)
>> +               LOG(Converter, Error) << "Failed to set scaler crop on dewarper "
>> +                                     << strerror(-ret);
>> +
> Does calling setSelection modify the rect? Do we need to check that at
> all or is it up to the caller to verify?

I am not sure here to be honest, If the selection rectangles get 
modified while applying, it's probably the caller's job to verify it.

Looking up the V4L2_SEL_FLAG_* flags, it seems there are ways to control 
the modification / constraints of the rectangles that get applied. So 
yes, a verification mechanism of what gets applied vs what was 
requested, needs to be present. If the rectangle is modified, we need to 
also look at  what are the  acceptable % of margins which we should 
allow - or print a error/warning otherwise?

>> +       return ret;
>> +}
>> +
>> +} /* namespace libcamera */
>> diff --git a/src/libcamera/converter/meson.build b/src/libcamera/converter/meson.build
>> index 2aa72fe4..175581b8 100644
>> --- a/src/libcamera/converter/meson.build
>> +++ b/src/libcamera/converter/meson.build
>> @@ -1,5 +1,6 @@
>>   # SPDX-License-Identifier: CC0-1.0
>>   
>>   libcamera_sources += files([
>> +        'converter_dw100.cpp',
>>           'converter_v4l2_m2m.cpp'
>>   ])
>> -- 
>> 2.44.0
>>
> Oh - wow, that's a small implementation! I guess that's the benefit of
> inheriting from M2MConvertor.
>
> That makes me wonder if ScalerCrop should be handled in the
> V4L2M2MConvertor generically instead ... but ... as we expect this class
> to be expanded for the dewarp, I think it's fine to be specialised here.
>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>