Disable the data cache before writing to Flash, in order to workaround
silicon errata 2.2.3: "Data cache might be corrupted during Flash memory
read-while-write operation". The data cache is conditionally re-enabled
once the write is completed.
This silicon bug has been encountered while stress testing the
implementation. Here are the events leading to the fault:
- Code is executing from Flash bank 1
- A write to Flash bank 2 is initiated
- The Cortex SysTick interrupt fires while waiting for Flash write
completion
In that case, the Flash controller will perform a read-while-write
operation in order to execute the ISR code. As the data cache is enabled
by default after reset, a corruption occurs due to the silicon bug,
leading to bizarre data bus faults or unaligned access faults inside
_timer_int_handler() or one of the functions called by the ISR.
Applying the workaround devised by ST fixes the problem.
Signed-off-by: Florian Vaussard <florian.vaussard@gmail.com>
2320973fea