gpu: nvgpu: Unify remove/shutdown codepaths

The following changes are part of the porting of the bind/unbind
functionality.

These changes reuse the shutdown codepaths in iGPU and dGPU and fix a locking
issue with in gk20a_busy() where the usage count can lead to a deadlock during
the driver shutdown. It fixes a racing condition with the gr/mm code by
invalidating the sw ready flag while holding the busy lock

JIRA: EVLR-1739

Change-Id: I62ce47378436b21f447f4cd93388759ed3f9bad1
Signed-off-by: David Nieto <dmartineznie@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1554959
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/clk/clk_arb.c

@@ -489,9 +489,8 @@ void nvgpu_clk_arb_cleanup_arbiter(struct gk20a *g)
 			nvgpu_kfree(g, arb->vf_table_pool[index].gpc2clk_points);
 			nvgpu_kfree(g, arb->vf_table_pool[index].mclk_points);
 		}
-	}
-
 		nvgpu_mutex_destroy(&g->clk_arb->pstate_lock);
+	}
 	nvgpu_kfree(g, g->clk_arb);
 	g->clk_arb = NULL;
 }

drivers/gpu/nvgpu/common/linux/module.c

@@ -640,6 +640,48 @@ static int gk20a_pm_unrailgate(struct device *dev)
 	return ret;
 }
 
+/*
+ * Idle the GPU in preparation of shutdown/remove.
+ * gk20a_driver_start_unload() does not idle the GPU, but instead changes the SW
+ * state to prevent further activity on the driver SW side.
+ * On driver removal quiesce() should be called after start_unload()
+ */
+int nvgpu_quiesce(struct gk20a *g)
+{
+	int err;
+	struct device *dev = dev_from_gk20a(g);
+
+	err = gk20a_wait_for_idle(g);
+	if (err) {
+		nvgpu_err(g, "failed to idle GPU, err=%d", err);
+		return err;
+	}
+
+	err = gk20a_fifo_disable_all_engine_activity(g, true);
+	if (err) {
+		nvgpu_err(g, "failed to disable engine activity, err=%d",
+			err);
+		return err;
+	}
+
+	err = gk20a_fifo_wait_engine_idle(g);
+	if (err) {
+		nvgpu_err(g, "failed to idle engines, err=%d",
+			err);
+		return err;
+	}
+
+	if (gk20a_gpu_is_virtual(dev))
+		err = vgpu_pm_prepare_poweroff(dev);
+	else
+		err = gk20a_pm_prepare_poweroff(dev);
+
+	if (err)
+		nvgpu_err(g, "failed to prepare for poweroff, err=%d",
+			err);
+	return err;
+}
+
 static void gk20a_pm_shutdown(struct platform_device *pdev)
 {
 	struct gk20a_platform *platform = platform_get_drvdata(pdev);
@@ -668,35 +710,9 @@ static void gk20a_pm_shutdown(struct platform_device *pdev)
 	/* Prevent more requests by disabling Runtime PM */
 	__pm_runtime_disable(&pdev->dev, false);
 
-	err = gk20a_wait_for_idle(g);
+	err = nvgpu_quiesce(g);
-	if (err) {
+	if (err)
-		nvgpu_err(g, "failed to idle GPU, err=%d", err);
 		goto finish;
-	}
-
-	err = gk20a_fifo_disable_all_engine_activity(g, true);
-	if (err) {
-		nvgpu_err(g, "failed to disable engine activity, err=%d",
-			err);
-		goto finish;
-	}
-
-	err = gk20a_fifo_wait_engine_idle(g);
-	if (err) {
-		nvgpu_err(g, "failed to idle engines, err=%d",
-			err);
-		goto finish;
-	}
-
-	if (gk20a_gpu_is_virtual(&pdev->dev))
-		err = vgpu_pm_prepare_poweroff(&pdev->dev);
-	else
-		err = gk20a_pm_prepare_poweroff(&pdev->dev);
-	if (err) {
-		nvgpu_err(g, "failed to prepare for poweroff, err=%d",
-			err);
-		goto finish;
-	}
 
 	err = gk20a_pm_railgate(&pdev->dev);
 	if (err)
@@ -854,6 +870,9 @@ void gk20a_driver_start_unload(struct gk20a *g)
 
 	down_write(&g->busy_lock);
 	__nvgpu_set_enabled(g, NVGPU_DRIVER_IS_DYING, true);
+	/* GR SW ready needs to be invalidated at this time with the busy lock
+	 * held to prevent a racing condition on the gr/mm code */
+	g->gr.sw_ready = false;
 	up_write(&g->busy_lock);
 
 	if (g->is_virtual)
@@ -979,18 +998,14 @@ static int gk20a_probe(struct platform_device *dev)
 	return 0;
 }
 
-static int __exit gk20a_remove(struct platform_device *pdev)
+int nvgpu_remove(struct device *dev, struct class *class)
 {
-	struct device *dev = &pdev->dev;
 	struct gk20a *g = get_gk20a(dev);
 	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
 	struct gk20a_platform *platform = gk20a_get_platform(dev);
 
 	gk20a_dbg_fn("");
 
-	if (gk20a_gpu_is_virtual(dev))
-		return vgpu_remove(pdev);
-
 	if (platform->has_cde)
 		gk20a_cde_destroy(l);
 
@@ -1001,16 +1016,11 @@ static int __exit gk20a_remove(struct platform_device *pdev)
 	if (IS_ENABLED(CONFIG_GK20A_DEVFREQ))
 		gk20a_scale_exit(dev);
 
-	if (g->remove_support)
-		g->remove_support(g);
-
-	gk20a_ce_destroy(g);
-
 #ifdef CONFIG_ARCH_TEGRA_18x_SOC
 	nvgpu_clk_arb_cleanup_arbiter(g);
 #endif
 
-	gk20a_user_deinit(dev, &nvgpu_class);
+	gk20a_user_deinit(dev, class);
 
 	gk20a_debug_deinit(g);
 
@@ -1026,14 +1036,28 @@ static int __exit gk20a_remove(struct platform_device *pdev)
 	if (platform->remove)
 		platform->remove(dev);
 
-	set_gk20a(pdev, NULL);
-	gk20a_put(g);
-
 	gk20a_dbg_fn("removed");
 
 	return 0;
 }
 
+static int __exit gk20a_remove(struct platform_device *pdev)
+{
+	int err;
+	struct device *dev = &pdev->dev;
+	struct gk20a *g = get_gk20a(dev);
+
+	if (gk20a_gpu_is_virtual(dev))
+		return vgpu_remove(pdev);
+
+	err = nvgpu_remove(dev, &nvgpu_class);
+
+	set_gk20a(pdev, NULL);
+	gk20a_put(g);
+
+	return err;
+}
+
 static struct platform_driver gk20a_driver = {
 	.probe = gk20a_probe,
 	.remove = __exit_p(gk20a_remove),

drivers/gpu/nvgpu/common/linux/module.h

@@ -19,6 +19,8 @@ struct device;
 int gk20a_pm_finalize_poweron(struct device *dev);
 void gk20a_remove_support(struct gk20a *g);
 void gk20a_driver_start_unload(struct gk20a *g);
+int nvgpu_quiesce(struct gk20a *g);
+int nvgpu_remove(struct device *dev, struct class *class);
 
 extern struct class nvgpu_class;
 

drivers/gpu/nvgpu/common/linux/pci.c

@@ -513,52 +513,34 @@ static int nvgpu_pci_probe(struct pci_dev *pdev,
 
 static void nvgpu_pci_remove(struct pci_dev *pdev)
 {
-	struct gk20a_platform *platform = gk20a_get_platform(&pdev->dev);
 	struct gk20a *g = get_gk20a(&pdev->dev);
-	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
+	struct device *dev = dev_from_gk20a(g);
+	int err;
 
-	gk20a_dbg(gpu_dbg_shutdown, "Removing nvgpu driver!\n");
+	/* no support yet for unbind if DGPU is in VGPU mode */
+	if (gk20a_gpu_is_virtual(dev))
+		return;
 
-	if (g->irqs_enabled)
+	/* only idle the GPU if the GPU is powered on */
-		disable_irq(g->irq_stall);
+	if (g->power_on) {
+		gk20a_driver_start_unload(g);
+		err = nvgpu_quiesce(g);
+		/* TODO: handle failure to idle */
+		WARN(err, "gpu failed to idle during driver removal");
+	}
 
-	devm_free_irq(&pdev->dev, g->irq_stall, g);
+	nvgpu_remove(dev, &nvgpu_pci_class);
 
 #if defined(CONFIG_PCI_MSI)
-	if (g->msi_enabled) {
+	if (g->msi_enabled)
 		pci_disable_msi(pdev);
-		g->msi_enabled = false;
+	else {
+		/* IRQ does not need to be enabled in MSI as the line is not
+		 * shared
+		 */
+		enable_irq(g->irq_stall);
 	}
 #endif
-	gk20a_dbg(gpu_dbg_shutdown, "IRQs disabled.\n");
-
-	/*
-	 * Wait for the driver to finish up all the IOCTLs it's working on
-	 * before cleaning up the driver's data structures.
-	 */
-	gk20a_driver_start_unload(g);
-	gk20a_dbg(gpu_dbg_shutdown, "Driver idle.\n");
-
-#ifdef CONFIG_ARCH_TEGRA_18x_SOC
-	nvgpu_clk_arb_cleanup_arbiter(g);
-#endif
-
-	gk20a_user_deinit(dev_from_gk20a(g), &nvgpu_pci_class);
-	gk20a_dbg(gpu_dbg_shutdown, "User de-init done.\b");
-
-#ifdef CONFIG_DEBUG_FS
-	debugfs_remove_recursive(l->debugfs);
-	debugfs_remove_recursive(l->debugfs_alias);
-#endif
-
-	nvgpu_remove_sysfs(dev_from_gk20a(g));
-
-	if (platform->remove)
-		platform->remove(dev_from_gk20a(g));
-	gk20a_dbg(gpu_dbg_shutdown, "Platform remove done.\b");
-
-	enable_irq(g->irq_stall);
-
 	gk20a_get_platform(&pdev->dev)->g = NULL;
 	gk20a_put(g);
 }