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. > > dev_dbg(&pdev->dev, "%s\n", __func__); > > @@ -31,14 +56,25 @@ static int simple_pm_bus_probe(struct platform_device *pdev) > > static int simple_pm_bus_remove(struct platform_device *pdev) > { > + const void *data = of_device_get_match_data(&pdev->dev); > + > + if (pdev->driver_override || data) > + return 0; > + > dev_dbg(&pdev->dev, "%s\n", __func__); > > pm_runtime_disable(&pdev->dev); > return 0; > } > > +#define ONLY_BUS ((void *) 1) /* Match if the device is only a bus. */ > + > static const struct of_device_id simple_pm_bus_of_match[] = { > { .compatible = "simple-pm-bus", }, > + { .compatible = "simple-bus", .data = ONLY_BUS }, > + { .compatible = "simple-mfd", .data = ONLY_BUS }, > + { .compatible = "isa", .data = ONLY_BUS }, > + { .compatible = "arm,amba-bus", .data = ONLY_BUS }, > { /* sentinel */ } > }; > MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match); > -- > 2.33.0.685.g46640cef36-goog >
