Rather than doing autoprobe within the driver model code, move it out to the board-init code. This makes it clear that it is a separate step from binding devices.
For now this is always done twice, before and after relocation, but we should discuss whether it might be possible to drop the post-relocation probe.
For boards with SPL, the autoprobe is still done there as well.
Note that with this change, autoprobe happens after the EVT_DM_POST_INIT_R/F events are sent, rather than before.
Link: https://lore.kernel.org/u-boot/20240626235717.272219-1-marex@denx.de/
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v3: - Add a link to the previous discussion - Add a summary of the design challenge in the DM docs - Use a simple return in initr_dm() - Add a comment to dm_probe_devices() - Expand comment to dm_autoprobe()
Changes in v2: - Add autoprobe to SPL also - Leave the function name the same - Fix 'Prove' typo - Update cover letter since SPL is now covered also - Update the documentation too, with a discussion link
common/board_f.c | 4 ++++ common/board_r.c | 2 +- common/spl/spl.c | 4 ++++ doc/develop/driver-model/design.rst | 17 +++++++++++++++++ drivers/core/root.c | 22 +++++++++++++++++++++- include/dm/root.h | 15 +++++++++++++++ 6 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/common/board_f.c b/common/board_f.c index 1e1aa08530a..974eb4f39e9 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -822,6 +822,10 @@ static int initf_dm(void) if (ret) return ret;
+ ret = dm_autoprobe(); + if (ret) + return ret; + if (IS_ENABLED(CONFIG_TIMER_EARLY)) { ret = dm_timer_init(); if (ret) diff --git a/common/board_r.c b/common/board_r.c index 62228a723e1..b761833294f 100644 --- a/common/board_r.c +++ b/common/board_r.c @@ -241,7 +241,7 @@ static int initr_dm(void) if (ret) return ret;
- return 0; + return dm_autoprobe(); } #endif
diff --git a/common/spl/spl.c b/common/spl/spl.c index 1ceb63daf31..c4256f237ee 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -500,6 +500,10 @@ static int spl_common_init(bool setup_malloc) debug("dm_init_and_scan() returned error %d\n", ret); return ret; } + + ret = dm_autoprobe(); + if (ret) + return ret; }
return 0; 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-mar... + Running stage ^^^^^^^^^^^^^
diff --git a/drivers/core/root.c b/drivers/core/root.c index 2d4f078f97f..045f8fcda65 100644 --- a/drivers/core/root.c +++ b/drivers/core/root.c @@ -281,6 +281,15 @@ void *dm_priv_to_rw(void *priv) } #endif
+/** + * dm_probe_devices() - Check whether to probe a device and all children + * + * Probes the device if DM_FLAG_PROBE_AFTER_BIND is enabled for it. Then scans + * all its children recursively to do the same. + * + * @dev: Device to (maybe) probe + * Return 0 if OK, -ve on error + */ static int dm_probe_devices(struct udevice *dev) { struct udevice *child; @@ -299,6 +308,17 @@ static int dm_probe_devices(struct udevice *dev) return 0; }
+int dm_autoprobe(void) +{ + int ret; + + ret = dm_probe_devices(gd->dm_root); + if (ret) + return log_msg_ret("pro", ret); + + return 0; +} + /** * dm_scan() - Scan tables to bind devices * @@ -331,7 +351,7 @@ static int dm_scan(bool pre_reloc_only) if (ret) return ret;
- return dm_probe_devices(gd->dm_root); + return 0; }
int dm_init_and_scan(bool pre_reloc_only) diff --git a/include/dm/root.h b/include/dm/root.h index b2f30a842f5..a71a2ebef85 100644 --- a/include/dm/root.h +++ b/include/dm/root.h @@ -136,6 +136,21 @@ int dm_scan_other(bool pre_reloc_only); */ int dm_init_and_scan(bool pre_reloc_only);
+/** + * dm_autoprobe() - Probe devices which are marked for probe-after-bind + * + * This probes all devices with a DM_FLAG_PROBE_AFTER_BIND flag. It checks the + * entire tree, so parent nodes need not have the flag set. + * + * It recursively probes parent nodes, so they do not need to have the flag + * set themselves. Since parents are always probed before children, if a child + * has the flag set, then its parent (and any devices up the chain to the root + * device) will be probed too. + * + * Return: 0 if OK, -ve on error + */ +int dm_autoprobe(void); + /** * dm_init() - Initialise Driver Model structures *