| commit | a0980d323ab319d2467e6bc79dfc9331b0649654 | [log] [tgz] |
|---|---|---|
| author | Timothy Chen <timothytim@google.com> | Wed Apr 07 22:34:02 2021 -0700 |
| committer | tjaychen <timothytim@google.com> | Thu Apr 08 18:54:09 2021 -0700 |
| tree | b660fd2669546a66b5fa47e8cdae59c3f7ce4026 | |
| parent | 0ac8b164592d9edeffaa51312316428ca6f7b563 [diff] |
[flash_ctrl] Correct behavior when buffer not enabled. When buffer is not enabled, the flash_phy_rd may erroneously return data to back to back transactions when it is not supposed to. This happens because even when buffers are not enabled, the read data is written into the holding FIFO between read and descramble stages. As a result, the return path falsely thinks the data is available and returns it. This causes an issue because even though the data is returned, the front door logic has already created 2 transactions to the flash, and a result, we have extra data returning. The buffer not enabled case can be caused by otp_ctrl not returning the flash controller's request for a key. This in turn can happen because entropy is not yet enabled. This latter point deserves a wider discussion as to the right solution. To fix this, the forward hint is used to distinguish when the data in the FIFO is valid vs when it is not. Signed-off-by: Timothy Chen <timothytim@google.com>
OpenTitan is an open source silicon Root of Trust (RoT) project. OpenTitan will make the silicon RoT design and implementation more transparent, trustworthy, and secure for enterprises, platform providers, and chip manufacturers. OpenTitan is administered by lowRISC CIC as a collaborative project to produce high quality, open IP for instantiation as a full-featured product. See the OpenTitan site and OpenTitan docs for more information about the project.
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