From ddef08dd00f5548f943422c86e4ffe67dd040b6c Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 27 Jul 2015 18:03:58 +0300 Subject: [PATCH] Driver core: wakeup the parent device before trying probe If the parent is still suspended when driver probe is attempted, the result may be failure. For example, if the parent is a PCI MFD device that has been suspended when we try to probe our device, any register reads will return 0xffffffff. To fix the problem, making sure the parent is always awake before attempting driver probe. Signed-off-by: Heikki Krogerus Signed-off-by: Rafael J. Wysocki Signed-off-by: Andy Shevchenko Signed-off-by: Lee Jones --- drivers/base/dd.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index a638bbb1a27a..2d6df1dd3852 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe); * * This function must be called with @dev lock held. When called for a * USB interface, @dev->parent lock must be held as well. + * + * If the device has a parent, runtime-resume the parent before driver probing. */ int driver_probe_device(struct device_driver *drv, struct device *dev) { @@ -410,10 +412,16 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); + if (dev->parent) + pm_runtime_get_sync(dev->parent); + pm_runtime_barrier(dev); ret = really_probe(dev, drv); pm_request_idle(dev); + if (dev->parent) + pm_runtime_put(dev->parent); + return ret; } @@ -507,11 +515,17 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) device_lock(dev); + if (dev->parent) + pm_runtime_get_sync(dev->parent); + bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); dev_dbg(dev, "async probe completed\n"); pm_request_idle(dev); + if (dev->parent) + pm_runtime_put(dev->parent); + device_unlock(dev); put_device(dev); @@ -541,6 +555,9 @@ static int __device_attach(struct device *dev, bool allow_async) .want_async = false, }; + if (dev->parent) + pm_runtime_get_sync(dev->parent); + ret = bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); if (!ret && allow_async && data.have_async) { @@ -557,6 +574,9 @@ static int __device_attach(struct device *dev, bool allow_async) } else { pm_request_idle(dev); } + + if (dev->parent) + pm_runtime_put(dev->parent); } out_unlock: device_unlock(dev); -- 2.20.1