The Teensy 4.1 board has an 8MB W25Q64JV as opposed to the 2MB flash
on the Teensy 4.0. This largely doensn't matter for TinyUsb, except
when you attempt to access any memory in the flash above the 2MB
boundary, when it fails with a hard fault.
Tested on SAMD51 - we can allow more packet sizes by checking that the set size value is greater than the requested packet size instead of exactly the same.
Not having this prevents the device from finishing the mounting process.
Tested on a SAMD51 and didn't seem to need to actually do anything in the close function.
- Stall now has priority over other interrupt responses
- Delete eunused hcd_edpt_busy
- Assert !ep->active when trying to start a new xfer
- Assert !ep->active when handling buff_status bits
- Set ep->xferred_len to 8 once a setup packet is finished so the data
structure is accurate
There were two problems:
- dma_running flag could be checked in USB interrupt (not set yet) then higher priority
interrupt could start transfer, check dma_running (not set yet) set it to true start
DMA; then when USB interrupt continues it starts another DMA that is not allowed
- when DMA is started some registers can't be safely accessed, read can yield invalid
values (SIZE.EPOUT, SIZE.EPISO)
current implementation could start DMA for one OUT endpoint then check that another
endpoint also has data and while DMA was not started right away, SIZE.EPOUT was copied
already to MAXCNT register. Later on when DMA was started not all data was read from
endpoint due to incorrect DMA size previously set.
To prevent both cases dma_running is changed in atomic way.
Only code that actually set this value to true starts DMA, code that tried and
had dma_running flag already set simply defers DMA start to USB task.
This eliminates also need to have mutex that was there to limit access to dma_running flag
to one task only.
transfer also now has started flag that is set only after dcd_edpt_xfer() sets up total_len
and actua_len. Previously USB interrupt was disabled when total_len and actual_len were
setup to prevent race condition when data arrived to ednpoint before transfer was setup
was finished.
