Relax AHB start address alignment limitation

Without this, unaligned AHB reads may return questionable data. This
seems to make a difference on 1000 series MCUs; without it, the taget-gen
test reliably fail on 1010 and 1040 MCUs. Not sure why the 1100 series
can get away without it.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index eb2963d..ffd2180 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -466,6 +466,10 @@ pub fn reset(flexspi: flexspi::Instance, flash_size_kib: usize, fifo_capacity_by
         RXCLKSRC: LOOPBACK_DQS,
     );
     ral::write_reg!(flexspi, flexspi, MCR1, SEQWAIT: 0xFFFF, AHBBUSWAIT: 0xFFFF);
+    // Fetch more data to satisfy any alignment requirements, no matter
+    // the AHB read burst start address. Helpful for users who are still
+    // using the AHB interface for reads.
+    ral::modify_reg!(flexspi, flexspi, AHBCR, READADDROPT: 1);
     ral::write_reg!(flexspi, flexspi, INTEN, 0);
     ral::write_reg!(flexspi, flexspi, INTR, u32::MAX);
     ral::write_reg!(