SPRUJ52C june 2022 – july 2023 AM69 , AM69A , TDA4AH-Q1 , TDA4AP-Q1 , TDA4VH-Q1 , TDA4VP-Q1
As described in Section 8.1.2.3 MSMC implements inclusive snoop filters for both memory-mapped SRAM and external memory shared space to limit the amount of required snoop traffic. Both the SRAM and external snoop filters encode the following states for each coherent memory block in their respective filtering structures:
As a safeguard MSMC provides a "Broadcast Mode" configuration that forces MSMC to treat all snoop filter entries as BROADCAST_UNIQUE. This results in snoops generated to all applicable coherent masters for snoop filter hits and misses. All allocations are killed when broadcast mode is set.
Because there are no cache allocations in this mode, inclusivity is lost. Coherency is maintained as long as broadcast mode is set but dynamic change of broadcast mode (that is, enable to disable) is not supported. System must invalidate L2 caches of all snoopable coherent masters connected to MSMC before they can disable broadcast mode again after enabling it to maintain coherence. To enable the broadcast mode feature the MSMC_COHCTRL[0] BCM bit should be set to 0x1.
Broadcast mode is expected to be used as a debug feature only as performance will be significantly impacted once this mode is enabled.