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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/develop/driver-model/design.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/doc/develop/driver-model/design.rst b/doc/develop/driver-model/design.rst index 8c2c81d7ac9..92f638a0204 100644 --- a/doc/develop/driver-model/design.rst +++ b/doc/develop/driver-model/design.rst @@ -842,6 +842,23 @@ steps (see device_probe()): cause the uclass to do some housekeeping to record the device as activated and 'known' by the uclass. +For some platforms, certain devices must be probed to get the platform into +a working state. To help with this, drivers marked with DM_FLAG_PROBE_AFTER_BIND +will be probed immediately after all devices are bound. For now, this happens in +SPL, before relocation and after relocation. See the call to ``dm_autoprobe()`` +for where this is done. + +The auto-probe feature is tricky because it bypasses the normal ordering of +probing. General, if device A (e.g. video) needs device B (e.g. clock), then +A's probe() method uses ``clk_get_by_index()`` and B is probed before A. But +A is only probed when it is used. Therefore care should be taken when using +auto-probe, limiting it to devices which truly are essential, such as power +domains or critical clocks. + +See here for more discussion of this feature: + +:Link: https://patchwork.ozlabs.org/project/uboot/patch/20240626235717.272219-1-marex@denx.de/ + Running stage ^^^^^^^^^^^^^ |