SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The BL merges the memory requests of the ISP master module to memory (read/write). The BL interfaces with all the ISP modules through a 32-bit-wide bus.
The ISP modules make memory requests of 32 bytes. Additional signals, SOF for read and EOF for write, are included to deal with boundary conditions in frame transitions.
The BL arbitration is divided into two parts: a bus hog and a fixed priority arbitration. Bus hog refers to the property of the buffer logic that gives higher priority to the module that last sent or received data. RSZ module MTC write port 0 and RSZ module MTC write port 1 are excluded from the bus hog.
The buffer logic is to be programmed to maximize the memory bandwidth: it makes maximum burst requests of 128 bytes (8 × 128 bits) for reads and writes. The BL can generate burst sizes of 2 × 128, 4 × 128, 6 × 128, and 8 × 128 bits.
The ISP interface supports burst sizes of only 1, 2, 4, and 8 × 128 bits. If the BL generates a 6 × 128-bit request, it is divided into a 4 × 128-bit request, followed by a 2 × 128-bit request.
To use the memory bandwidth efficiently, the BL interfaces with the memory through a high-bandwidth bus (128 bits wide).
The BL handles memory requests for the following modules:
From a use case point of view, the following sharing and priority arrangement is used. All reads have higher priority than writes; for reads: IPIPEIF > ISIF-LSC, and for writes: ISIF > IPIPE > RSZ 0 > RSZ 1 > H3A.
The BL can generate a static or a dynamic MFlag signal. The MFlag signal is used by the ISS arbitration to consider the urgency of the requests coming from the ISP. The dynamic MFlag feature is enabled from the ISP5_CTRL[21] MFLAG bit.
Figure 9-172 shows the BL top-level block diagram. The figure highlights the two clock domains that are used.
The BL module has no registers. The configurations come from the top level of the ISP. See Section 9.3.4, ISS ISP Register Manual, for register details.