[PATCH v4 0/3] Add test to verify probe of devices from discoverable buses

[Nícolas F. R. A. Prado]

This is part of an effort to improve detection of regressions impacting
device probe on all platforms. The recently merged DT kselftest [3]
detects probe issues for all devices described statically in the DT.
That leaves out devices discovered at run-time from discoverable buses.

This is where this test comes in. All of the devices that are connected
through discoverable buses (ie USB and PCI), and which are internal and
therefore always present, can be described based on their position in
the system topology in a per-platform YAML file so they can be checked
for. The test will check that the device has been instantiated and bound
to a driver.

Patch 1 introduces the test. Patch 2 and 3 add the device definitions
for the google,spherion machine (Acer Chromebook 514) and XPS 13 as
examples.

This is the output from the test running on Spherion:

TAP version 13
Using board file: boards/google,spherion.yaml
1..8
ok 1 /usb2-controller@11200000/1.4.1/camera.device
ok 2 /usb2-controller@11200000/1.4.1/camera.0.driver
ok 3 /usb2-controller@11200000/1.4.1/camera.1.driver
ok 4 /usb2-controller@11200000/1.4.2/bluetooth.device
ok 5 /usb2-controller@11200000/1.4.2/bluetooth.0.driver
ok 6 /usb2-controller@11200000/1.4.2/bluetooth.1.driver
ok 7 /pci-controller@11230000/0.0/0.0/wifi.device
ok 8 /pci-controller@11230000/0.0/0.0/wifi.driver
Totals: pass:8 fail:0 xfail:0 xpass:0 skip:0 error:0

[3] https://lore.kernel.org/all/20230828211424.2964562-1-nfraprado@xxxxxxxxxxxxx/

Changes in v4:
- Dropped RFC tag
- Fixed 'busses' misspelling
- Link to v3: https://lore.kernel.org/all/20231227123643.52348-1-nfraprado@xxxxxxxxxxxxx

Changes in v3:
- Reverted approach of encoding stable device reference in test file
from device match fields (from modalias) back to HW topology (from v1)
- Changed board file description to YAML
- Rewrote test script in python to handle YAML and support x86 platforms
- Link to v2: https://lore.kernel.org/all/20231127233558.868365-1-nfraprado@xxxxxxxxxxxxx

Changes in v2:
- Changed approach of encoding stable device reference in test file from
HW topology to device match fields (the ones from modalias)
- Better documented test format
- Link to v1: https://lore.kernel.org/all/20231024211818.365844-1-nfraprado@xxxxxxxxxxxxx

---
Nícolas F. R. A. Prado (3):
      kselftest: Add test to verify probe of devices from discoverable buses
      kselftest: devices: Add sample board file for google,spherion
      kselftest: devices: Add sample board file for XPS 13 9300

 tools/testing/selftests/Makefile                   |   1 +
 tools/testing/selftests/devices/Makefile           |   4 +
 .../devices/boards/Dell Inc.,XPS 13 9300.yaml      |  40 +++
 .../selftests/devices/boards/google,spherion.yaml  |  50 ++++
 tools/testing/selftests/devices/ksft.py            |  90 ++++++
 .../selftests/devices/test_discoverable_devices.py | 318 +++++++++++++++++++++
 6 files changed, 503 insertions(+)
---
base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
change-id: 20240122-discoverable-devs-ksft-9d501e312688

Best regards,
-- 
Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>