accel/qaic: Expand DRM device lifecycle

Currently the QAIC DRM device registers itself when the MHI QAIC_CONTROL
channel becomes available. This is when the device is able to process
workloads. However, the DRM driver also provides the debugfs interface
bootlog for the device. If the device fails to boot to the QSM (which
brings up the MHI QAIC_CONTROL channel), the bootlog won't be available for
debugging why it failed to boot.

Change when the DRM device registers itself from when QAIC_CONTROL is
available to when the card is first probed on the PCI bus. Additionally,
make the DRM driver persist through reset/error cases so the driver
doesn't have to be reloaded to access the card again. Send
KOBJ_ONLINE/OFFLINE uevents so userspace can know when DRM device is
ready to handle requests.

Signed-off-by: Carl Vanderlip <[e-mail]>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <[e-mail]>
Reviewed-by: Jeffrey Hugo <[e-mail]>
Signed-off-by: Jeffrey Hugo <[e-mail]>
Reviewed-by: Jacek Lawrynowicz <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/accel/qaic/qaic.rst

···
 uAPI
 ====
 
+QAIC creates an accel device per phsyical PCIe device. This accel device exists
+for as long as the PCIe device is known to Linux.
+
+The PCIe device may not be in the state to accept requests from userspace at
+all times. QAIC will trigger KOBJ_ONLINE/OFFLINE uevents to advertise when the
+device can accept requests (ONLINE) and when the device is no longer accepting
+requests (OFFLINE) because of a reset or other state transition.
+
 QAIC defines a number of driver specific IOCTLs as part of the userspace API.
-This section describes those APIs.
 
 DRM_IOCTL_QAIC_MANAGE
   This IOCTL allows userspace to send a NNC request to the QSM. The call will

drivers/accel/qaic/mhi_controller.c

···
 		pci_err(qdev->pdev, "Fatal error received from device. Attempting to recover\n");
 	/* this event occurs in non-atomic context */
 	if (reason == MHI_CB_SYS_ERROR)
-		qaic_dev_reset_clean_local_state(qdev, true);
+		qaic_dev_reset_clean_local_state(qdev);
 }
 
 static int mhi_reset_and_async_power_up(struct mhi_controller *mhi_cntrl)

drivers/accel/qaic/qaic.h

···
 void release_dbc(struct qaic_device *qdev, u32 dbc_id);
 
 void wake_all_cntl(struct qaic_device *qdev);
-void qaic_dev_reset_clean_local_state(struct qaic_device *qdev, bool exit_reset);
+void qaic_dev_reset_clean_local_state(struct qaic_device *qdev);
 
 struct drm_gem_object *qaic_gem_prime_import(struct drm_device *dev, struct dma_buf *dma_buf);
 

drivers/accel/qaic/qaic_drv.c

···
 #include <linux/idr.h>
 #include <linux/interrupt.h>
 #include <linux/list.h>
+#include <linux/kobject.h>
 #include <linux/kref.h>
 #include <linux/mhi.h>
 #include <linux/module.h>
···
 MODULE_PARM_DESC(datapath_polling, "Operate the datapath in polling mode");
 static bool link_up;
 static DEFINE_IDA(qaic_usrs);
-
-static int qaic_create_drm_device(struct qaic_device *qdev, s32 partition_id);
-static void qaic_destroy_drm_device(struct qaic_device *qdev, s32 partition_id);
 
 static void free_usr(struct kref *kref)
 {
···
 
 	qddev->partition_id = partition_id;
 
-	/*
-	 * drm_dev_unregister() sets the driver data to NULL and
-	 * drm_dev_register() does not update the driver data. During a SOC
-	 * reset drm dev is unregistered and registered again leaving the
-	 * driver data to NULL.
-	 */
-	dev_set_drvdata(to_accel_kdev(qddev), drm->accel);
 	ret = drm_dev_register(drm, 0);
 	if (ret)
 		pci_dbg(qdev->pdev, "drm_dev_register failed %d\n", ret);
···
 	struct drm_device *drm = to_drm(qddev);
 	struct qaic_user *usr;
 
-	drm_dev_get(drm);
 	drm_dev_unregister(drm);
 	qddev->partition_id = 0;
 	/*
···
 		mutex_lock(&qddev->users_mutex);
 	}
 	mutex_unlock(&qddev->users_mutex);
-	drm_dev_put(drm);
 }
 
 static int qaic_mhi_probe(struct mhi_device *mhi_dev, const struct mhi_device_id *id)
···
 
 	qdev = pci_get_drvdata(to_pci_dev(mhi_dev->mhi_cntrl->cntrl_dev));
 
-	qdev->dev_state = QAIC_ONLINE;
-
 	dev_set_drvdata(&mhi_dev->dev, qdev);
 	qdev->cntl_ch = mhi_dev;
 
···
 		return ret;
 	}
 
+	qdev->dev_state = QAIC_BOOT;
 	ret = get_cntl_version(qdev, NULL, &major, &minor);
 	if (ret || major != CNTL_MAJOR || minor > CNTL_MINOR) {
 		pci_err(qdev->pdev, "%s: Control protocol version (%d.%d) not supported. Supported version is (%d.%d). Ret: %d\n",
···
 		ret = -EINVAL;
 		goto close_control;
 	}
-
-	ret = qaic_create_drm_device(qdev, QAIC_NO_PARTITION);
+	qdev->dev_state = QAIC_ONLINE;
+	kobject_uevent(&(to_accel_kdev(qdev->qddev))->kobj, KOBJ_ONLINE);
 
 	return ret;
 
···
 {
 	int i;
 
+	kobject_uevent(&(to_accel_kdev(qdev->qddev))->kobj, KOBJ_OFFLINE);
 	qdev->dev_state = QAIC_OFFLINE;
 	/* wake up any waiters to avoid waiting for timeouts at sync */
 	wake_all_cntl(qdev);
···
 	synchronize_srcu(&qdev->dev_lock);
 }
 
-void qaic_dev_reset_clean_local_state(struct qaic_device *qdev, bool exit_reset)
+void qaic_dev_reset_clean_local_state(struct qaic_device *qdev)
 {
 	int i;
 
 	qaic_notify_reset(qdev);
 
-	/* remove drmdevs to prevent new users from coming in */
-	qaic_destroy_drm_device(qdev, QAIC_NO_PARTITION);
-
 	/* start tearing things down */
 	for (i = 0; i < qdev->num_dbc; ++i)
 		release_dbc(qdev, i);
-
-	if (exit_reset)
-		qdev->dev_state = QAIC_ONLINE;
 }
 
 static void cleanup_qdev(struct qaic_device *qdev)
···
 	if (!qdev)
 		return NULL;
 
+	qdev->dev_state = QAIC_OFFLINE;
 	if (id->device == PCI_DEV_AIC100) {
 		qdev->num_dbc = 16;
 		qdev->dbc = devm_kcalloc(&pdev->dev, qdev->num_dbc, sizeof(*qdev->dbc), GFP_KERNEL);
···
 		goto cleanup_qdev;
 	}
 
+	ret = qaic_create_drm_device(qdev, QAIC_NO_PARTITION);
+	if (ret)
+		goto cleanup_qdev;
+
 	qdev->mhi_cntrl = qaic_mhi_register_controller(pdev, qdev->bar_0, mhi_irq,
 						       qdev->single_msi);
 	if (IS_ERR(qdev->mhi_cntrl)) {
 		ret = PTR_ERR(qdev->mhi_cntrl);
-		goto cleanup_qdev;
+		goto cleanup_drm_dev;
 	}
 
 	return 0;
 
+cleanup_drm_dev:
+	qaic_destroy_drm_device(qdev, QAIC_NO_PARTITION);
 cleanup_qdev:
 	cleanup_qdev(qdev);
 	return ret;
···
 	if (!qdev)
 		return;
 
-	qaic_dev_reset_clean_local_state(qdev, false);
+	qaic_dev_reset_clean_local_state(qdev);
+	qaic_destroy_drm_device(qdev, QAIC_NO_PARTITION);
 	qaic_mhi_free_controller(qdev->mhi_cntrl, link_up);
 	cleanup_qdev(qdev);
 }
···
 
 	qaic_notify_reset(qdev);
 	qaic_mhi_start_reset(qdev->mhi_cntrl);
-	qaic_dev_reset_clean_local_state(qdev, false);
+	qaic_dev_reset_clean_local_state(qdev);
 }
 
 static void qaic_pci_reset_done(struct pci_dev *pdev)
 {
 	struct qaic_device *qdev = pci_get_drvdata(pdev);
 
-	qdev->dev_state = QAIC_ONLINE;
 	qaic_mhi_reset_done(qdev->mhi_cntrl);
 }