| commit | 7d681e5cfe327d0e348325faaadcaa9f9d1b472b | [log] [tgz] |
|---|---|---|
| author | Alexander Williams <awill@google.com> | Mon Feb 14 07:56:08 2022 -0800 |
| committer | tjaychen <timothytim@google.com> | Tue Mar 08 10:03:03 2022 -0800 |
| tree | 40e908d9629319b6c5beaae90f1cf27e61977793 | |
| parent | 1938c40267b74458d3f0a7b80892ac9921424bd9 [diff] |
[usbdev] Enable defaulting to NAK for OUT transactions Add a bit to change the behavior for OUT transactions to default to NAK without software intervention, for safe communication of responses to the host. Before this commit, the device could incorrectly communicate acceptance of a packet to the host if the firmware did not take action in time. Defaulting to NAK gives the firmware time, since this is a nonbinding condition--The device is merely saying, "Please try again later." Clear the rxenable_out bit in hardware when a packet is received. Update software code to match. This change could have deleterious effects on performance in some cases, but priority is given to safe handling of responses. For interfaces that may perform transactions when a buffer is available, do not set the set_nak_out bit for the corresponding endpoints. Signed-off-by: Alexander Williams <awill@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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