@@ -286,6 +286,138 @@ void drm_minor_release(struct drm_minor *minor)
* 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_get() and drm_dev_put() only carefully.
+ *
+ * Display driver example
+ * ~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * The following example shows a typical structure of a DRM display driver.
+ * The example focus on the probe() function and the other functions that is
+ * almost always present and serves as a demonstration of devm_drm_dev_init()
+ * usage with its accompanying drm_driver->release callback.
+ *
+ * .. code-block:: c
+ *
+ * struct driver_device {
+ * struct drm_device drm;
+ * void *userspace_facing;
+ * struct clk *pclk;
+ * };
+ *
+ * static void driver_drm_release(struct drm_device *drm)
+ * {
+ * struct driver_device *priv = container_of(...);
+ *
+ * drm_mode_config_cleanup(drm);
+ * drm_dev_fini(drm);
+ * kfree(priv->userspace_facing);
+ * kfree(priv);
+ * }
+ *
+ * static struct drm_driver driver_drm_driver = {
+ * [...]
+ * .release = driver_drm_release,
+ * };
+ *
+ * static int driver_probe(struct platform_device *pdev)
+ * {
+ * struct driver_device *priv;
+ * struct drm_device *drm;
+ * int ret;
+ *
+ * [
+ * devm_kzalloc() can't be used here because the drm_device
+ * lifetime can exceed the device lifetime if driver unbind
+ * happens when userspace still has open file descriptors.
+ * ]
+ * priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ * if (!priv)
+ * return -ENOMEM;
+ *
+ * drm = &priv->drm;
+ *
+ * ret = devm_drm_dev_init(&pdev->dev, drm, &driver_drm_driver);
+ * if (ret) {
+ * kfree(drm);
+ * return ret;
+ * }
+ *
+ * drm_mode_config_init(drm);
+ *
+ * priv->userspace_facing = kzalloc(..., GFP_KERNEL);
+ * if (!priv->userspace_facing)
+ * return -ENOMEM;
+ *
+ * priv->pclk = devm_clk_get(dev, "PCLK");
+ * if (IS_ERR(priv->pclk))
+ * return PTR_ERR(priv->pclk);
+ *
+ * [ Further setup, display pipeline etc ]
+ *
+ * platform_set_drvdata(pdev, drm);
+ *
+ * drm_mode_config_reset(drm);
+ *
+ * ret = drm_dev_register(drm);
+ * if (ret)
+ * return ret;
+ *
+ * drm_fbdev_generic_setup(drm, 32);
+ *
+ * return 0;
+ * }
+ *
+ * [ This function is called before the devm_ resources are released ]
+ * static int driver_remove(struct platform_device *pdev)
+ * {
+ * struct drm_device *drm = platform_get_drvdata(pdev);
+ *
+ * drm_dev_unregister(drm);
+ * drm_atomic_helper_shutdown(drm)
+ *
+ * return 0;
+ * }
+ *
+ * [ This function is called on kernel restart and shutdown ]
+ * static void driver_shutdown(struct platform_device *pdev)
+ * {
+ * drm_atomic_helper_shutdown(platform_get_drvdata(pdev));
+ * }
+ *
+ * static int __maybe_unused driver_pm_suspend(struct device *dev)
+ * {
+ * return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
+ * }
+ *
+ * static int __maybe_unused driver_pm_resume(struct device *dev)
+ * {
+ * drm_mode_config_helper_resume(dev_get_drvdata(dev));
+ *
+ * return 0;
+ * }
+ *
+ * static const struct dev_pm_ops driver_pm_ops = {
+ * SET_SYSTEM_SLEEP_PM_OPS(driver_pm_suspend, driver_pm_resume)
+ * };
+ *
+ * static struct platform_driver driver_driver = {
+ * .driver = {
+ * [...]
+ * .pm = &driver_pm_ops,
+ * },
+ * .probe = driver_probe,
+ * .remove = driver_remove,
+ * .shutdown = driver_shutdown,
+ * };
+ * module_platform_driver(driver_driver);
+ *
+ * Drivers that want to support device unplugging (USB, DT overlay unload) should
+ * use drm_dev_unplug() instead of drm_dev_unregister(). The driver must protect
+ * regions that is accessing device resources to prevent use after they're
+ * released. This is done using drm_dev_enter() and drm_dev_exit(). There is one
+ * shortcoming however, drm_dev_unplug() marks the drm_device as unplugged before
+ * drm_atomic_helper_shutdown() is called. This means that if the disable code
+ * paths are protected, they will not run on regular driver module unload,
+ * possibily leaving the hardware enabled.
*/
/**