diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 30401f927156..11f5bfb68ecb 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -138,14 +138,10 @@ At the core of every DRM driver is a drm_driver structure. Drivers typically statically initialize a drm_driver structure, - and then pass it to one of the drm_*_init() functions - to register it with the DRM subsystem. - - - Newer drivers that no longer require a drm_bus - structure can alternatively use the low-level device initialization and - registration functions such as drm_dev_alloc() and - drm_dev_register() directly. + and then pass it to drm_dev_alloc() to allocate a + device instance. After the device instance is fully initialized it can be + registered (which makes it accessible from userspace) using + drm_dev_register(). The drm_driver structure contains static @@ -296,83 +292,12 @@ char *date; - Device Registration - - A number of functions are provided to help with device registration. - The functions deal with PCI and platform devices, respectively. - -!Edrivers/gpu/drm/drm_pci.c -!Edrivers/gpu/drm/drm_platform.c - - New drivers that no longer rely on the services provided by the - drm_bus structure can call the low-level - device registration functions directly. The - drm_dev_alloc() function can be used to allocate - and initialize a new drm_device structure. - Drivers will typically want to perform some additional setup on this - structure, such as allocating driver-specific data and storing a - pointer to it in the DRM device's dev_private - field. Drivers should also set the device's unique name using the - drm_dev_set_unique() function. After it has been - set up a device can be registered with the DRM subsystem by calling - drm_dev_register(). This will cause the device to - be exposed to userspace and will call the driver's - .load() implementation. When a device is - removed, the DRM device can safely be unregistered and freed by calling - drm_dev_unregister() followed by a call to - drm_dev_unref(). - + Device Instance and Driver Handling +!Pdrivers/gpu/drm/drm_drv.c driver instance overview !Edrivers/gpu/drm/drm_drv.c Driver Load - - The load method is the driver and device - initialization entry point. The method is responsible for allocating and - initializing driver private data, performing resource allocation and - mapping (e.g. acquiring - clocks, mapping registers or allocating command buffers), initializing - the memory manager (), installing - the IRQ handler (), setting up - vertical blanking handling (), mode - setting () and initial output - configuration (). - - - If compatibility is a concern (e.g. with drivers converted over from - User Mode Setting to Kernel Mode Setting), care must be taken to prevent - device initialization and control that is incompatible with currently - active userspace drivers. For instance, if user level mode setting - drivers are in use, it would be problematic to perform output discovery - & configuration at load time. Likewise, if user-level drivers - unaware of memory management are in use, memory management and command - buffer setup may need to be omitted. These requirements are - driver-specific, and care needs to be taken to keep both old and new - applications and libraries working. - - int (*load) (struct drm_device *, unsigned long flags); - - The method takes two arguments, a pointer to the newly created - drm_device and flags. The flags are used to - pass the driver_data field of the device id - corresponding to the device passed to drm_*_init(). - Only PCI devices currently use this, USB and platform DRM drivers have - their load method called with flags to 0. - - - Driver Private Data - - The driver private hangs off the main - drm_device structure and can be used for - tracking various device-specific bits of information, like register - offsets, command buffer status, register state for suspend/resume, etc. - At load time, a driver may simply allocate one and set - drm_device.dev_priv - appropriately; it should be freed and - drm_device.dev_priv - set to NULL when the driver is unloaded. - - IRQ Registration @@ -465,6 +390,18 @@ char *date; + + Bus-specific Device Registration and PCI Support + + A number of functions are provided to help with device registration. + The functions deal with PCI and platform devices respectively and are + only provided for historical reasons. These are all deprecated and + shouldn't be used in new drivers. Besides that there's a few + helpers for pci drivers. + +!Edrivers/gpu/drm/drm_pci.c +!Edrivers/gpu/drm/drm_platform.c + diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 9ad823fcde87..d01f8d6c5fdb 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -396,16 +396,52 @@ void drm_minor_release(struct drm_minor *minor) drm_dev_unref(minor->dev); } +/** + * DOC: driver instance overview + * + * A device instance for a drm driver is represented by struct &drm_device. This + * is allocated with drm_dev_alloc(), usually from bus-specific ->probe() + * callbacks implemented by the driver. The driver then needs to initialize all + * the various subsystems for the drm device like memory management, vblank + * handling, modesetting support and intial output configuration plus obviously + * initialize all the corresponding hardware bits. An important part of this is + * also calling drm_dev_set_unique() to set the userspace-visible unique name of + * this device instance. Finally when everything is up and running and ready for + * userspace the device instance can be published using drm_dev_register(). + * + * There is also deprecated support for initalizing device instances using + * bus-specific helpers and the ->load() callback. But due to + * backwards-compatibility needs the device instance have to be published too + * early, which requires unpretty global locking to make safe and is therefore + * only support for existing drivers not yet converted to the new scheme. + * + * When cleaning up a device instance everything needs to be done in reverse: + * First unpublish the device instance with drm_dev_unregister(). Then clean up + * any other resources allocated at device initialization and drop the driver's + * reference to &drm_device using drm_dev_unref(). + * + * Note that the lifetime rules for &drm_device instance has still a lot of + * historical baggage. Hence use the reference counting provided by + * drm_dev_ref() and drm_dev_unref() only carefully. + * + * Also note that embedding of &drm_device is currently not (yet) supported (but + * it would be easy to add). Drivers can store driver-private data in the + * dev_priv field of &drm_device. + */ + /** * drm_put_dev - Unregister and release a DRM device * @dev: DRM device * * Called at module unload time or when a PCI device is unplugged. * - * Use of this function is discouraged. It will eventually go away completely. - * Please use drm_dev_unregister() and drm_dev_unref() explicitly instead. - * * Cleans up all DRM device, calling drm_lastclose(). + * + * Note: Use of this function is deprecated. It will eventually go away + * completely. Please use drm_dev_unregister() and drm_dev_unref() explicitly + * instead to make sure that the device isn't userspace accessible any more + * while teardown is in progress, ensuring that userspace can't access an + * inconsistent state. */ void drm_put_dev(struct drm_device *dev) { @@ -518,7 +554,9 @@ static void drm_fs_inode_free(struct inode *inode) * * Allocate and initialize a new DRM device. No device registration is done. * Call drm_dev_register() to advertice the device to user space and register it - * with other core subsystems. + * with other core subsystems. This should be done last in the device + * initialization sequence to make sure userspace can't access an inconsistent + * state. * * The initial ref-count of the object is 1. Use drm_dev_ref() and * drm_dev_unref() to take and drop further ref-counts. @@ -673,6 +711,12 @@ EXPORT_SYMBOL(drm_dev_unref); * * Never call this twice on any device! * + * NOTE: To ensure backward compatibility with existing drivers method this + * function calls the ->load() method after registering the device nodes, + * creating race conditions. Usage of the ->load() methods is therefore + * deprecated, drivers must perform all initialization before calling + * drm_dev_register(). + * * RETURNS: * 0 on success, negative error code on failure. */ @@ -720,6 +764,9 @@ EXPORT_SYMBOL(drm_dev_register); * Unregister the DRM device from the system. This does the reverse of * drm_dev_register() but does not deallocate the device. The caller must call * drm_dev_unref() to drop their final reference. + * + * This should be called first in the device teardown code to make sure + * userspace can't access the device instance any more. */ void drm_dev_unregister(struct drm_device *dev) { diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c index 1b1bd42b0368..fcd2a86acd2c 100644 --- a/drivers/gpu/drm/drm_pci.c +++ b/drivers/gpu/drm/drm_pci.c @@ -266,6 +266,9 @@ void drm_pci_agp_destroy(struct drm_device *dev) * then register the character device and inter module information. * Try and register, if we fail to register, backout previous work. * + * NOTE: This function is deprecated, please use drm_dev_alloc() and + * drm_dev_register() instead and remove your ->load() callback. + * * Return: 0 on success or a negative error code on failure. */ int drm_get_pci_dev(struct pci_dev *pdev, const struct pci_device_id *ent, @@ -326,6 +329,10 @@ EXPORT_SYMBOL(drm_get_pci_dev); * Initializes a drm_device structures, registering the stubs and initializing * the AGP device. * + * NOTE: This function is deprecated. Modern modesetting drm drivers should use + * pci_register_driver() directly, this function only provides shadow-binding + * support for old legacy drivers on top of that core pci function. + * * Return: 0 on success or a negative error code on failure. */ int drm_pci_init(struct drm_driver *driver, struct pci_driver *pdriver) @@ -435,6 +442,10 @@ EXPORT_SYMBOL(drm_pci_init); * * Unregisters one or more devices matched by a PCI driver from the DRM * subsystem. + * + * NOTE: This function is deprecated. Modern modesetting drm drivers should use + * pci_unregister_driver() directly, this function only provides shadow-binding + * support for old legacy drivers on top of that core pci function. */ void drm_pci_exit(struct drm_driver *driver, struct pci_driver *pdriver) { diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c index 5314c9d5fef4..644169e1a029 100644 --- a/drivers/gpu/drm/drm_platform.c +++ b/drivers/gpu/drm/drm_platform.c @@ -95,6 +95,9 @@ EXPORT_SYMBOL(drm_platform_set_busid); * subsystem, initializing a drm_device structure and calling the driver's * .load() function. * + * NOTE: This function is deprecated, please use drm_dev_alloc() and + * drm_dev_register() instead and remove your ->load() callback. + * * Return: 0 on success or a negative error code on failure. */ int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device)