Upstream synchronization [v0.20] #73

roma-jam · 2025-11-26T09:42:09Z

Description

Update to v0.20.0.

Changes include pure tag 0.20.0 merged on top of the branch release/v0.19 (with partial limitation fix from #69).

Notes

~~As the release "v0.19.0~2" wasn't pulblished yet, this changes will take place over the stable release v0.18.0~6.~~ Published 24.11.2025

The merging logic:

Create the branch release/v0.20 from the release/v0.19, tag v0.19.0.2
Make a merge from the pure tag 0.20.0 from the upstream
Solve the conflicts with listing them in here
Create a PR to the release/v0.20 (this PR)

Limitations

Blocking

stdio.h for snprintf() isn't included when CFG_TUSB_DEBUG_PRINTF is defined (fix(tusb_debug): Added stdio.h include when CFG_TUSB_DEBUG_PRINTF [WIP] #74)
dcd_deinit() WEAK function returns false by default. Causes an assert in tud_deinit(rhport) because of the TU_VERIFY(dcd_deinit(rhport));, (change(usbd): Changed return value to true for weak dcd_deinit() (quick fix) hathach/tinyusb#3370)

Non-blocking

not implemented logic of dcd_deinit() in dcd_dwc2.c. For us, it is not critical, as we reconfigure the controller during the next dcd_init(). (feature(dcd_dwc2): Added the dcd_deinit() stub call to avoid assert [WIP] #75)
unaligned cache sync for CDC class driver during CDC control request E (7258) cache: esp_cache_msync(116): start address: 0x4ff2eb07, or the size: 0x40 is(are) not aligned with cache line size (0x40)B

Additional notes

Conflicts, found during merging with 0.20.0:

tusb_common.h:

Fixed more alert found by PVS-Studio (accept incoming changes)
fix Make inclusion of stdio.h optional hathach/tinyusb#2942, include stdio if CFG_TUSB_DEBUG > 0 and CFG_TUSB_DEBUG_PRINTF is not defined (accept incoming changes)

dcd_dwc2.c:

Fixed more alert found by PVS-Studio (accept incoming changes)

The initial motivation for doing this is to remove the `used` flag in the TD. If we use this flag, we end up being required to read from TDs that the OHCI controller might be modifying (i.e. the OHCI controller logically owns the TD). This happens when we try to allocate a new, empty TD while the OHCI host controller is working on a transfer. Move the `used` flag to `gtd_extra_data_t`. This data is only used by the CPU, and the OHCI controller never accesses it. The existing allocation method for TDs does *not* put an empty TD onto each ED (i.e it does *not* do what is shown in Figure 5-6 of the OHCI specification). Instead, the NextTD field of the last TD is set to 0. The TailP field of the ED is also set to 0. This works in many cases. However, this implementation means that the CPU may end up trying to write to the NextTD field of an in-progress transfer while the OHCI host controller logically owns it. Change the implementation to use an empty TD, as suggested by the specification, for endpoints other than EP0. This avoids the above issue. It is not necessary to make the change for EP0 because only at most one TD can ever be pending at a time. The above change should also remove the need for the stall workaround. In the future, we want to modify the code to access EDs through an uncached mapping. Because uncached mappings are slow, we want to access EDs as little as possible. Currently, when a TD completes, we access an ED in order to figure out the device address and endpoint number of the TD which was completed. Because moving `used` to `gtd_extra_data_t` necessitates expanding it, we have enough room to also store the device address and endpoint number of the TD. This patch does so. With the above two changes, we no longer need to access an ED when a TD completes. Also remove the `index` field from TDs as it is no longer necessary.

This code is written very carefully to always use an uncached view of memory to read/write EDs. An uncached view must *always* be used, or else cache behavior can corrupt the ED. As part of this change, combine access into as few word-sized accesses as possible. This makes the code perform better. Doing this involves giving type names to the bitfields that make up the ED's data words.