SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
It is possible to discard part of the received data for pixel and attribute data (that is, header and control data cannot be discarded). This is performed inside the write DMA cropping block. The feature is enabled by configuring:
The cropping block discards unwanted data and modifies data TAG to preserve integrity. For example, when pixel data is processed:
Cropping is mainly intended to enable partial DPCM decompression and to reduce storage requirements / power consumption when digital zoom is used. No dummy data will be written, if the programmed size is less than what is received. Refer to Section 9.2.3.8.1, CAL Partial DPCM Decompression, for more details.
Cropping may also be used for attribute data. It cannot be used for header data. It is SW responsibility to not use cropping for header data. HW does not perform any additional checks.
The DMA accumulates data independently for contexts until an OCP write transaction can be generated. That is the case when enough data is available to generate a full burst or when the end of an image line has been reached.
Data cropping is performed after the DPCM encoder. Therefore, horizontal skipping cannot be used when data is DPCM encoded. Otherwise, it will be not possible to decode the data, unless reference samples have been stored to resume decode.