From 8a1ed14ebf8c4e916fac8cb34b1eebbe60624db4 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Wed, 6 Jun 2018 14:38:47 -0700 Subject: Documentation: update firmware loader fallback reference The firmware loader has a fallback mechanism, and it now has some proper kdoc, but we forgot to update the Documentation to use the new kdoc. Fix that. Signed-off-by: Luis R. Rodriguez Signed-off-by: Greg Kroah-Hartman --- Documentation/driver-api/firmware/fallback-mechanisms.rst | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst index d35fed65eae9..8b041d0ab426 100644 --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst @@ -92,7 +92,7 @@ the loading file. The firmware device used to help load firmware using sysfs is only created if direct firmware loading fails and if the fallback mechanism is enabled for your -firmware request, this is set up with fw_load_from_user_helper(). It is +firmware request, this is set up with :c:func:`firmware_fallback_sysfs`. It is important to re-iterate that no device is created if a direct filesystem lookup succeeded. @@ -108,6 +108,11 @@ firmware_data_read() and firmware_loading_show() are just provided for the test_firmware driver for testing, they are not called in normal use or expected to be used regularly by userspace. +firmware_fallback_sysfs +----------------------- +.. kernel-doc:: drivers/base/firmware_loader/fallback.c + :functions: firmware_fallback_sysfs + Firmware kobject uevent fallback mechanism ========================================== -- cgit v1.2.3 From 25b4e70dcce92168eab4d8113817bb4dd130ebd2 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Mon, 9 Jul 2018 09:41:48 -0600 Subject: driver core: allow stopping deferred probe after init Deferred probe will currently wait forever on dependent devices to probe, but sometimes a driver will never exist. It's also not always critical for a driver to exist. Platforms can rely on default configuration from the bootloader or reset defaults for things such as pinctrl and power domains. This is often the case with initial platform support until various drivers get enabled. There's at least 2 scenarios where deferred probe can render a platform broken. Both involve using a DT which has more devices and dependencies than the kernel supports. The 1st case is a driver may be disabled in the kernel config. The 2nd case is the kernel version may simply not have the dependent driver. This can happen if using a newer DT (provided by firmware perhaps) with a stable kernel version. Deferred probe issues can be difficult to debug especially if the console has dependencies or userspace fails to boot to a shell. There are also cases like IOMMUs where only built-in drivers are supported, so deferring probe after initcalls is not needed. The IOMMU subsystem implemented its own mechanism to handle this using OF_DECLARE linker sections. This commit adds makes ending deferred probe conditional on initcalls being completed or a debug timeout. Subsystems or drivers may opt-in by calling driver_deferred_probe_check_init_done() instead of unconditionally returning -EPROBE_DEFER. They may use additional information from DT or kernel's config to decide whether to continue to defer probe or not. The timeout mechanism is intended for debug purposes and WARNs loudly. The remaining deferred probe pending list will also be dumped after the timeout. Not that this timeout won't work for the console which needs to be enabled before userspace starts. However, if the console's dependencies are resolved, then the kernel log will be printed (as opposed to no output). Cc: Alexander Graf Signed-off-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/kernel-parameters.txt | 9 ++++ drivers/base/dd.c | 59 +++++++++++++++++++++++++ include/linux/device.h | 2 + 3 files changed, 70 insertions(+) (limited to 'Documentation') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index efc7aa7a0670..e83ef4648ea4 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -804,6 +804,15 @@ Defaults to the default architecture's huge page size if not specified. + deferred_probe_timeout= + [KNL] Debugging option to set a timeout in seconds for + deferred probe to give up waiting on dependencies to + probe. Only specific dependencies (subsystems or + drivers) that have opted in will be ignored. A timeout of 0 + will timeout at the end of initcalls. This option will also + dump out devices still on the deferred probe list after + retrying. + dhash_entries= [KNL] Set number of hash buckets for dentry cache. diff --git a/drivers/base/dd.c b/drivers/base/dd.c index e85705e84407..fb62f1be40d3 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -55,6 +55,7 @@ static LIST_HEAD(deferred_probe_pending_list); static LIST_HEAD(deferred_probe_active_list); static atomic_t deferred_trigger_count = ATOMIC_INIT(0); static struct dentry *deferred_devices; +static bool initcalls_done; /* * In some cases, like suspend to RAM or hibernation, It might be reasonable @@ -219,6 +220,51 @@ static int deferred_devs_show(struct seq_file *s, void *data) } DEFINE_SHOW_ATTRIBUTE(deferred_devs); +static int deferred_probe_timeout = -1; +static int __init deferred_probe_timeout_setup(char *str) +{ + deferred_probe_timeout = simple_strtol(str, NULL, 10); + return 1; +} +__setup("deferred_probe_timeout=", deferred_probe_timeout_setup); + +/** + * driver_deferred_probe_check_state() - Check deferred probe state + * @dev: device to check + * + * Returns -ENODEV if init is done and all built-in drivers have had a chance + * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug + * timeout has expired, or -EPROBE_DEFER if none of those conditions are met. + * + * Drivers or subsystems can opt-in to calling this function instead of directly + * returning -EPROBE_DEFER. + */ +int driver_deferred_probe_check_state(struct device *dev) +{ + if (initcalls_done) { + if (!deferred_probe_timeout) { + dev_WARN(dev, "deferred probe timeout, ignoring dependency"); + return -ETIMEDOUT; + } + dev_warn(dev, "ignoring dependency for device, assuming no driver"); + return -ENODEV; + } + return -EPROBE_DEFER; +} + +static void deferred_probe_timeout_work_func(struct work_struct *work) +{ + struct device_private *private, *p; + + deferred_probe_timeout = 0; + driver_deferred_probe_trigger(); + flush_work(&deferred_probe_work); + + list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) + dev_info(private->device, "deferred probe pending"); +} +static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); + /** * deferred_probe_initcall() - Enable probing of deferred devices * @@ -235,6 +281,19 @@ static int deferred_probe_initcall(void) driver_deferred_probe_trigger(); /* Sort as many dependencies as possible before exiting initcalls */ flush_work(&deferred_probe_work); + initcalls_done = true; + + /* + * Trigger deferred probe again, this time we won't defer anything + * that is optional + */ + driver_deferred_probe_trigger(); + flush_work(&deferred_probe_work); + + if (deferred_probe_timeout > 0) { + schedule_delayed_work(&deferred_probe_timeout_work, + deferred_probe_timeout * HZ); + } return 0; } late_initcall(deferred_probe_initcall); diff --git a/include/linux/device.h b/include/linux/device.h index 575c5a35ece5..d2acc78d279b 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -339,6 +339,8 @@ struct device *driver_find_device(struct device_driver *drv, struct device *start, void *data, int (*match)(struct device *dev, void *data)); +int driver_deferred_probe_check_state(struct device *dev); + /** * struct subsys_interface - interfaces to device functions * @name: name of the device function -- cgit v1.2.3 From 7930eb919feb59b8c799cb3085d0e9f7b5ae34d1 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Mon, 9 Jul 2018 09:41:49 -0600 Subject: dt-bindings: pinctrl: add a 'pinctrl-use-default' property Pin setup may be optional in some cases such as the reset default works or the pin setup is done by the bootloader. In these cases, it is optional for the OS to support managing the pin controller and pin setup. In order to support this scenario, add a property 'pinctrl-use-default' to indicate that the pin configuration is optional. Signed-off-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt index ad9bbbba36e9..cef2b5855d60 100644 --- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt @@ -103,6 +103,12 @@ Optional properties: #pinctrl-cells: Number of pin control cells in addition to the index within the pin controller device instance +pinctrl-use-default: Boolean. Indicates that the OS can use the boot default + pin configuration. This allows using an OS that does not have a + driver for the pin controller. This property can be set either + globally for the pin controller or in child nodes for individual + pin group control. + Pin controller devices should contain the pin configuration nodes that client devices reference. -- cgit v1.2.3