On Wed, Nov 10, 2021 at 12:24 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote: > > On Wed, Nov 10, 2021 at 4:16 AM Abel Vesa <abelvesa@xxxxxxxxxx> wrote: > > > > On 21-09-28 17:07:33, Saravana Kannan wrote: > > > fw_devlink could end up creating device links for bus only devices. > > > However, bus only devices don't get probed and can block probe() or > > > sync_state() [1] call backs of other devices. To avoid this, probe these > > > devices using the simple-pm-bus driver. > > > > > > However, there are instances of devices that are not simple buses (they get > > > probed by their specific drivers) that also list the "simple-bus" (or other > > > bus only compatible strings) in their compatible property to automatically > > > populate their child devices. We still want these devices to get probed by > > > their specific drivers. So, we make sure this driver only probes devices > > > that are only buses. > > > > > > [1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@xxxxxxxxxxxxxx/ > > > Fixes: c442a0d18744 ("driver core: Set fw_devlink to "permissive" behavior by default") > > > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > > > Tested-by: Saravana Kannan <saravanak@xxxxxxxxxx> > > > Tested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > > > --- > > > drivers/bus/simple-pm-bus.c | 42 ++++++++++++++++++++++++++++++++++--- > > > 1 file changed, 39 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c > > > index 01a3d0cd08ed..6b8d6257ed8a 100644 > > > --- a/drivers/bus/simple-pm-bus.c > > > +++ b/drivers/bus/simple-pm-bus.c > > > @@ -13,11 +13,36 @@ > > > #include <linux/platform_device.h> > > > #include <linux/pm_runtime.h> > > > > > > - > > > static int simple_pm_bus_probe(struct platform_device *pdev) > > > { > > > - const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev); > > > - struct device_node *np = pdev->dev.of_node; > > > + const struct device *dev = &pdev->dev; > > > + const struct of_dev_auxdata *lookup = dev_get_platdata(dev); > > > + struct device_node *np = dev->of_node; > > > + const struct of_device_id *match; > > > + > > > + /* > > > + * Allow user to use driver_override to bind this driver to a > > > + * transparent bus device which has a different compatible string > > > + * that's not listed in simple_pm_bus_of_match. We don't want to do any > > > + * of the simple-pm-bus tasks for these devices, so return early. > > > + */ > > > + if (pdev->driver_override) > > > + return 0; > > > + > > > + match = of_match_device(dev->driver->of_match_table, dev); > > > + /* > > > + * These are transparent bus devices (not simple-pm-bus matches) that > > > + * have their child nodes populated automatically. So, don't need to > > > + * do anything more. We only match with the device if this driver is > > > + * the most specific match because we don't want to incorrectly bind to > > > + * a device that has a more specific driver. > > > + */ > > > + if (match && match->data) { > > > + if (of_property_match_string(np, "compatible", match->compatible) == 0) > > > + return 0; > > > + else > > > + return -ENODEV; > > > + } > > > > This change is breaking the expected behavior for the already existent > > simple-bus nodes. All the simple-bus compatibles should be replaced now > > to simple-pm-bus. In my case, on some i.MX8 platforms, without the > > devlink, the devices suspend sequence changes (and even breaks). > > > > To avoid breaking the already existent simple-bus nodes, maybe the logic > > should've been reversed: keep the simple-bus as is and add another > > compatible, IDK, something like simple-trasnparent-bus, or something. > > The intent of this change IS to affect existing simple-bus nodes (but > not in the way it's affecting you). But if it's breaking stuff, we > obviously need to fix it. > > I have a hunch on what's going on in your case, but can you point me > to the specific simple-bus node that's getting affected? I'm expecting > it to be a simple-bus node that gets added AFTER this driver is > registered at device_initcall (module_init gets converted to > device_initcall). > > Also, can you try this hack patch to see if it helps your case? > https://lore.kernel.org/lkml/CAGETcx9U130Oq-umrvXME4JhEpO0Wadoki3kNxx=0-YvTR6PtQ@xxxxxxxxxxxxxx/ > > I have some thoughts on how I could fix this, but I need to think > about a few cases. Hi Abel, Friendly reminder. -Saravana
