usb_selftest_ospi_rw Directory Reference

Directory dependency graph for usb_selftest_ospi_rw:

Directories
	inc
	src

Detailed Description

The non-volatile write-path member of the USB self-loop matrix: it exercises the host-to-device bulk-OUT data phase (SCSI WRITE(10)) landing on the onboard OSPI flash. The two USB ports are cabled to each other and one image runs both stacks – USBFS (J11) exposes a single writable logical unit backed by a 32 KiB window of the IS25LX512M at xSPI CS1, USBHS (J7) is the polled first-party host stack, which writes a deterministic per-LBA pattern across the window in bursts and then reads it back and byte-checks every sector. Because the host writes the data and reads it back off real flash, this is the validation that the device bulk-OUT WRITE data phase round-trips onto persistent storage rather than RAM.

The OSPI window and why the write path is program-only

The device worker provisions OSPI once at boot: activate the octo-SPI mux via the U15 I/O expander, init the xSPI pins, ra8_xspi_init in 1S-1S-1S, read the JEDEC id, then erase the whole window once. Each subsequent WRITE(10) is therefore a fast program-only path – a per-write 4 KiB erase would blow the host's BOT timeout.

The window at 0x00200000 is scratch, clear of both flash_journal at offset 0 and the read-only image usb_selftest_ospi writes at 0x00100000. It is erased and rewritten every run, so the test never touches another app's data.

The driver fix this validates

A host-to-device bulk-OUT data phase needs four things working together, all in ra8_usb, the DCD and cmake/usbx.cmake:

1. Host MPS – chunk the data-out at the device's enumerated endpoint wMaxPacketSize (FS = 64), not the host controller's speed ceiling (HS = 512). ra8_usb_host_bulk_out ships one packet per call.
2. Device DBLB – double-buffer the device bulk-OUT pipe so the host's next packet lands in bank B while the ISR drains bank A.
3. Loop-drain – the DCD drains every ready OUT bank per interrupt.
4. Single-chunk buffer – UX_SLAVE_REQUEST_DATA_MAX_LENGTH is large enough to keep a typical WRITE in one device transfer, with no inter-chunk gap.

Pinout

FS device: P4_07 VBUS sense, P5_00 VBUSEN GPIO LOW, P8_14/P8_15 data (PSEL usb_fs). HS host: SW4-8 Host via the U15 expander, PD07 HIGH (U18 powers J7), P4_08 VBUS sense (PSEL usb_hs). Console: PD_02/PD_03 SCI8. OSPI: xSPI CS1 to the onboard IS25LX512M via the U15 octo-SPI mux. The device advertises VID 0x1209 with a per-app PID; bench use only.