| commit | cb6c456456939d77589c65a40d2c907a7dd30486 | [log] [tgz] |
|---|---|---|
| author | Martin Lueker-Boden <martin.lueker-boden@wdc.com> | Mon Oct 11 16:40:34 2021 -0700 |
| committer | Martin Lueker-Boden <47870387+martin-lueker@users.noreply.github.com> | Tue Oct 12 13:44:15 2021 -0700 |
| tree | d2947e97b5fdeb59aafa0f6f13fc7a1f886c90c8 | |
| parent | a984a95a4cde498e6144beac9b150b2542e4d8b4 [diff] |
[spi_host, rtl] Clarify transitions for "bypassable" idle states The SPI_HOST idle states `Idle` and `IdleCSBActive` are bypassable, meaning if their exit condition is satisfied, the FSM can transition immediately from the pre-idle to the next post-idle state. (See the SPI_HOST specification for more details.) This commit simply refactors the previous implementation for better clarity and robustness. Prior to this commit there was duplicated code in both the idle states, as well as their preceding states. This makes the code both harder to follow and more bug-prone, as disparate edits can be made in either place. This commit adds new signals: state_after_idle and state_after_idle_csb_active to compute the next state when the exit condition for both states. These signals are then explicitly examined in the pre-idle state to perform the idle-bypass if appropriate. A bypass can only occur if command_ready is asserted, the command_ready signal is also asserted up to one clock cycle before entering an idle state So the always_comb blocks that compute state_after_idle_csb_active therefore also perform the neccesary computation for the command_ready signal. Which is somewhat complex because of the possibility of an aborted CSAAT segment. (command_ready is always high in the idle state or one cycle before the idle state) ---- In addition this commit changes how configuration changes are identified. Previously a configuration change was assumed to happen only when CSID changed between two command segments. The FSM now also checks for any changes in the configopts structure passed in with the command segment. Signed-off-by: Martin Lueker-Boden <martin.lueker-boden@wdc.com>
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