tree 6104a66c53700a6fc65ea6779c65f48ad606681c
parent 244ccebd23eeb2b1bdae70e911d6252174f4c258
author Timothy Chen <timothytim@google.com> 1592896451 -0700
committer tjaychen <timothytim@google.com> 1592940010 -0700

[flash] Design updates and clean-up

- Clean-up and fix the usage of sizing parameters.  Previous
  design represented flash sizes in bus words, leading to an
  incorrect alignment of page boundaries.  This PR changes
  the parameters to flash word size base and explicitly declares
  the bus widths separately.

- Also add an arbiter count between host and controller arbitration.
  Since host reads are critical to performance, the past design
  always favored hosts, with the understanding under the right access
  patterns this could lead to deadlock.  Recent system changes indeed
  led to such an arbitration starvation, so a counter is added to
  ensure controller will not be starved.

- Round robin is still not preferred because controller does not need
  access priority as long as it can "eventually" finish.

Signed-off-by: Timothy Chen <timothytim@google.com>