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pipeline: rpi: pisp: Support LSB-aligned unpacked RAW streams #365

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pipeline: rpi: pisp: Support LSB-aligned unpacked RAW streams #365

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29 changes: 25 additions & 4 deletions src/libcamera/pipeline/rpi/pisp/pisp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -140,8 +140,14 @@ pisp_image_format_config toPiSPImageFormat(V4L2DeviceFormat &format)
BayerFormat bayer = BayerFormat::fromPixelFormat(pix);
switch (bayer.packing) {
case BayerFormat::Packing::None:
/*
* Unpacked samples with fewer than 16 bits are aligned
* to the LSB: the Frontend output shifts them right,
* the Backend input shifts them back left.
*/
image.format = PISP_IMAGE_FORMAT_BPS_16 +
PISP_IMAGE_FORMAT_UNCOMPRESSED;
PISP_IMAGE_FORMAT_UNCOMPRESSED +
(16 - bayer.bitDepth) * PISP_IMAGE_FORMAT_SHIFT_1;
break;
case BayerFormat::Packing::PISP1:
image.format = PISP_IMAGE_FORMAT_COMPRESSION_MODE_1;
Expand Down Expand Up @@ -1210,11 +1216,26 @@ PiSPCameraData::platformValidate(RPi::RPiCameraConfiguration *rpiConfig) const

StreamConfiguration *rawStream = rawStreams[0].cfg;
BayerFormat bayer = BayerFormat::fromPixelFormat(rawStream->pixelFormat);
const V4L2VideoDevice *cfe = cfe_[Cfe::Output0].dev();
unsigned int sensorBits =
MediaBusFormatInfo::info(rpiConfig->sensorFormat_.code).bitsPerPixel;

/*
* Unpacked 10 to 14-bit samples at the sensor bit depth are
* aligned to the LSB of 16-bit words, which the Frontend output
* produces with a right shift, if the CFE offers the format.
*/
bool lsbAligned = bayer.packing == BayerFormat::Packing::None &&
bayer.bitDepth == sensorBits &&
sensorBits > 8 && sensorBits < 16 &&
cfe->toV4L2PixelFormat(bayer.toPixelFormat()).isValid();

/*
* We cannot output CSI2 packed or non 16-bit output from the frontend,
* so signal the output as unpacked 16-bits in these cases.
* We cannot output CSI2 packed or other non 16-bit output from the
* frontend, so signal the output as unpacked 16-bits in these cases.
*/
if (bayer.packing == BayerFormat::Packing::CSI2 || bayer.bitDepth != 16) {
if (!lsbAligned &&
(bayer.packing == BayerFormat::Packing::CSI2 || bayer.bitDepth != 16)) {
bayer.packing = (bayer.packing == BayerFormat::Packing::CSI2) ?
BayerFormat::Packing::PISP1 : BayerFormat::Packing::None;
bayer.bitDepth = 16;
Expand Down