drm/{i915, xe}: Implement fbdev emulation as in-kernel client

Replace all code that initializes or releases fbdev emulation
throughout the driver. Instead initialize the fbdev client by a
single call to intel_fbdev_setup() after i915 has registered its
DRM device. Just like similar code in other drivers, i915 fbdev
emulation now acts like a regular DRM client. Do the same for xe.

The fbdev client setup consists of the initial preparation and the
hot-plugging of the display. The latter creates the fbdev device
and sets up the fbdev framebuffer. The setup performs display
hot-plugging once. If no display can be detected, DRM probe helpers
re-run the detection on each hotplug event.

A call to drm_client_dev_unregister() releases all in-kernel clients
automatically. No further action is required within i915. If the fbdev
framebuffer has been fully set up, struct fb_ops.fb_destroy implements
the release. For partially initialized emulation, the fbdev client
reverts the initial setup. Do the same for xe and remove its call to
intel_fbdev_fini().

v8:
- setup client in intel_display_driver_register (Jouni)
- mention xe in commit message

v7:
- update xe driver
- reword commit message

v6:
- use 'i915' for i915 device (Jouni)
- remove unnecessary code for non-atomic mode setting (Jouni, Ville)
- fix function name in commit message (Jouni)

v3:
-  as before, silently ignore devices without displays

v2:
-  let drm_client_register() handle initial hotplug
-  fix driver name in error message (Jani)
-  fix non-fbdev build (kernel test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240409081029.17843-7-tzimmermann@suse.de
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: tdz

drivers/gpu/drm/i915/display/intel_display.c

@@ -85,7 +85,6 @@
 #include "intel_dvo.h"
 #include "intel_fb.h"
 #include "intel_fbc.h"
-#include "intel_fbdev.h"
 #include "intel_fdi.h"
 #include "intel_fifo_underrun.h"
 #include "intel_frontbuffer.h"

drivers/gpu/drm/i915/display/intel_display_driver.c

@@ -516,10 +516,6 @@ int intel_display_driver_probe(struct drm_i915_private *i915)
 
 	intel_overlay_setup(i915);
 
-	ret = intel_fbdev_init(&i915->drm);
-	if (ret)
-		return ret;
-
 	/* Only enable hotplug handling once the fbdev is fully set up. */
 	intel_hpd_init(i915);
 
@@ -546,16 +542,6 @@ void intel_display_driver_register(struct drm_i915_private *i915)
 
 	intel_display_debugfs_register(i915);
 
-	/*
-	 * Some ports require correctly set-up hpd registers for
-	 * detection to work properly (leading to ghost connected
-	 * connector status), e.g. VGA on gm45.  Hence we can only set
-	 * up the initial fbdev config after hpd irqs are fully
-	 * enabled. We do it last so that the async config cannot run
-	 * before the connectors are registered.
-	 */
-	intel_fbdev_initial_config_async(i915);
-
 	/*
 	 * We need to coordinate the hotplugs with the asynchronous
 	 * fbdev configuration, for which we use the
@@ -564,6 +550,8 @@ void intel_display_driver_register(struct drm_i915_private *i915)
 	drm_kms_helper_poll_init(&i915->drm);
 	intel_hpd_poll_disable(i915);
 
+	intel_fbdev_setup(i915);
+
 	intel_display_device_info_print(DISPLAY_INFO(i915),
 					DISPLAY_RUNTIME_INFO(i915), &p);
 }
@@ -599,9 +587,6 @@ void intel_display_driver_remove_noirq(struct drm_i915_private *i915)
 	 */
 	intel_hpd_poll_fini(i915);
 
-	/* poll work can call into fbdev, hence clean that up afterwards */
-	intel_fbdev_fini(i915);
-
 	intel_unregister_dsm_handler();
 
 	/* flush any delayed tasks or pending work */
@@ -642,7 +627,6 @@ void intel_display_driver_unregister(struct drm_i915_private *i915)
 
 	drm_client_dev_unregister(&i915->drm);
 
-	intel_fbdev_unregister(i915);
 	/*
 	 * After flushing the fbdev (incl. a late async config which
 	 * will have delayed queuing of a hotplug event), then flush

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -24,7 +24,6 @@
  *     David Airlie
  */
 
-#include <linux/async.h>
 #include <linux/console.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
@@ -39,6 +38,7 @@
 #include <linux/vga_switcheroo.h>
 
 #include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -58,7 +58,6 @@ struct intel_fbdev {
 	struct intel_framebuffer *fb;
 	struct i915_vma *vma;
 	unsigned long vma_flags;
-	async_cookie_t cookie;
 	int preferred_bpp;
 
 	/* Whether or not fbdev hpd processing is temporarily suspended */
@@ -135,6 +134,26 @@ static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	return i915_gem_fb_mmap(obj, vma);
 }
 
+static void intel_fbdev_fb_destroy(struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct intel_fbdev *ifbdev = container_of(fb_helper, struct intel_fbdev, helper);
+
+	drm_fb_helper_fini(&ifbdev->helper);
+
+	/*
+	 * We rely on the object-free to release the VMA pinning for
+	 * the info->screen_base mmaping. Leaking the VMA is simpler than
+	 * trying to rectify all the possible error paths leading here.
+	 */
+	intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
+	drm_framebuffer_remove(&ifbdev->fb->base);
+
+	drm_client_release(&fb_helper->client);
+	drm_fb_helper_unprepare(&ifbdev->helper);
+	kfree(ifbdev);
+}
+
 __diag_push();
 __diag_ignore_all("-Woverride-init", "Allow field initialization overrides for fb ops");
 
@@ -147,6 +166,7 @@ static const struct fb_ops intelfb_ops = {
 	.fb_pan_display = intel_fbdev_pan_display,
 	__FB_DEFAULT_DEFERRED_OPS_DRAW(intel_fbdev),
 	.fb_mmap = intel_fbdev_mmap,
+	.fb_destroy = intel_fbdev_fb_destroy,
 };
 
 __diag_pop();
@@ -158,7 +178,6 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	struct intel_framebuffer *intel_fb = ifbdev->fb;
 	struct drm_device *dev = helper->dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
 	const struct i915_gtt_view view = {
 		.type = I915_GTT_VIEW_NORMAL,
 	};
@@ -250,7 +269,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	ifbdev->vma_flags = flags;
 
 	intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
-	vga_switcheroo_client_fb_set(pdev, info);
+
 	return 0;
 
 out_unpin:
@@ -276,26 +295,6 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
 	.fb_dirty = intelfb_dirty,
 };
 
-static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
-{
-	/* We rely on the object-free to release the VMA pinning for
-	 * the info->screen_base mmaping. Leaking the VMA is simpler than
-	 * trying to rectify all the possible error paths leading here.
-	 */
-
-	drm_fb_helper_fini(&ifbdev->helper);
-
-	if (ifbdev->vma)
-		intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
-
-	if (ifbdev->fb)
-		drm_framebuffer_remove(&ifbdev->fb->base);
-
-	drm_client_release(&ifbdev->helper.client);
-	drm_fb_helper_unprepare(&ifbdev->helper);
-	kfree(ifbdev);
-}
-
 /*
  * Build an intel_fbdev struct using a BIOS allocated framebuffer, if possible.
  * The core display code will have read out the current plane configuration,
@@ -459,16 +458,6 @@ static void intel_fbdev_suspend_worker(struct work_struct *work)
 				true);
 }
 
-static void intel_fbdev_sync(struct intel_fbdev *ifbdev)
-{
-	if (!ifbdev->cookie)
-		return;
-
-	/* Only serialises with all preceding async calls, hence +1 */
-	async_synchronize_cookie(ifbdev->cookie + 1);
-	ifbdev->cookie = 0;
-}
-
 /* Suspends/resumes fbdev processing of incoming HPD events. When resuming HPD
  * processing, fbdev will perform a full connector reprobe if a hotplug event
  * was received while HPD was suspended.
@@ -559,8 +548,6 @@ static int intel_fbdev_output_poll_changed(struct drm_device *dev)
 	if (!ifbdev)
 		return -EINVAL;
 
-	intel_fbdev_sync(ifbdev);
-
 	mutex_lock(&ifbdev->hpd_lock);
 	send_hpd = !ifbdev->hpd_suspended;
 	ifbdev->hpd_waiting = true;
@@ -580,7 +567,6 @@ static int intel_fbdev_restore_mode(struct drm_i915_private *dev_priv)
 	if (!ifbdev)
 		return -EINVAL;
 
-	intel_fbdev_sync(ifbdev);
 	if (!ifbdev->vma)
 		return -ENOMEM;
 
@@ -598,7 +584,20 @@ static int intel_fbdev_restore_mode(struct drm_i915_private *dev_priv)
  */
 
 static void intel_fbdev_client_unregister(struct drm_client_dev *client)
-{ }
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = fb_helper->dev;
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
+
+	if (fb_helper->info) {
+		vga_switcheroo_client_fb_set(pdev, NULL);
+		drm_fb_helper_unregister_info(fb_helper);
+	} else {
+		drm_fb_helper_unprepare(fb_helper);
+		drm_client_release(&fb_helper->client);
+		kfree(fb_helper);
+	}
+}
 
 static int intel_fbdev_client_restore(struct drm_client_dev *client)
 {
@@ -616,7 +615,31 @@ static int intel_fbdev_client_restore(struct drm_client_dev *client)
 
 static int intel_fbdev_client_hotplug(struct drm_client_dev *client)
 {
-	return intel_fbdev_output_poll_changed(client->dev);
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = client->dev;
+	struct pci_dev *pdev = to_pci_dev(dev->dev);
+	int ret;
+
+	if (dev->fb_helper)
+		return intel_fbdev_output_poll_changed(dev);
+
+	ret = drm_fb_helper_init(dev, fb_helper);
+	if (ret)
+		goto err_drm_err;
+
+	ret = drm_fb_helper_initial_config(fb_helper);
+	if (ret)
+		goto err_drm_fb_helper_fini;
+
+	vga_switcheroo_client_fb_set(pdev, fb_helper->info);
+
+	return 0;
+
+err_drm_fb_helper_fini:
+	drm_fb_helper_fini(fb_helper);
+err_drm_err:
+	drm_err(dev, "Failed to setup i915 fbdev emulation (ret=%d)\n", ret);
+	return ret;
 }
 
 static const struct drm_client_funcs intel_fbdev_client_funcs = {
@@ -626,91 +649,43 @@ static const struct drm_client_funcs intel_fbdev_client_funcs = {
 	.hotplug	= intel_fbdev_client_hotplug,
 };
 
-int intel_fbdev_init(struct drm_device *dev)
+void intel_fbdev_setup(struct drm_i915_private *i915)
 {
-	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_device *dev = &i915->drm;
 	struct intel_fbdev *ifbdev;
 	int ret;
 
-	if (drm_WARN_ON(dev, !HAS_DISPLAY(dev_priv)))
-		return -ENODEV;
+	if (!HAS_DISPLAY(i915))
+		return;
 
 	ifbdev = kzalloc(sizeof(*ifbdev), GFP_KERNEL);
 	if (!ifbdev)
-		return -ENOMEM;
-
-	mutex_init(&ifbdev->hpd_lock);
+		return;
 	drm_fb_helper_prepare(dev, &ifbdev->helper, 32, &intel_fb_helper_funcs);
 
+	i915->display.fbdev.fbdev = ifbdev;
+	INIT_WORK(&i915->display.fbdev.suspend_work, intel_fbdev_suspend_worker);
+	mutex_init(&ifbdev->hpd_lock);
 	if (intel_fbdev_init_bios(dev, ifbdev))
 		ifbdev->helper.preferred_bpp = ifbdev->preferred_bpp;
 	else
 		ifbdev->preferred_bpp = ifbdev->helper.preferred_bpp;
 
 	ret = drm_client_init(dev, &ifbdev->helper.client, "intel-fbdev",
 			      &intel_fbdev_client_funcs);
-	if (ret)
+	if (ret) {
+		drm_err(dev, "Failed to register client: %d\n", ret);
 		goto err_drm_fb_helper_unprepare;
+	}
 
-	ret = drm_fb_helper_init(dev, &ifbdev->helper);
-	if (ret)
-		goto err_drm_client_release;
-
-	dev_priv->display.fbdev.fbdev = ifbdev;
-	INIT_WORK(&dev_priv->display.fbdev.suspend_work, intel_fbdev_suspend_worker);
+	drm_client_register(&ifbdev->helper.client);
 
-	return 0;
+	return;
 
-err_drm_client_release:
-	drm_client_release(&ifbdev->helper.client);
 err_drm_fb_helper_unprepare:
 	drm_fb_helper_unprepare(&ifbdev->helper);
+	mutex_destroy(&ifbdev->hpd_lock);
 	kfree(ifbdev);
-	return ret;
-}
-
-static void intel_fbdev_initial_config(void *data, async_cookie_t cookie)
-{
-	struct intel_fbdev *ifbdev = data;
-
-	/* Due to peculiar init order wrt to hpd handling this is separate. */
-	if (drm_fb_helper_initial_config(&ifbdev->helper))
-		intel_fbdev_unregister(to_i915(ifbdev->helper.dev));
-}
-
-void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
-
-	if (!ifbdev)
-		return;
-
-	ifbdev->cookie = async_schedule(intel_fbdev_initial_config, ifbdev);
-}
-
-void intel_fbdev_unregister(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
-
-	if (!ifbdev)
-		return;
-
-	intel_fbdev_set_suspend(&dev_priv->drm, FBINFO_STATE_SUSPENDED, true);
-
-	if (!current_is_async())
-		intel_fbdev_sync(ifbdev);
-
-	drm_fb_helper_unregister_info(&ifbdev->helper);
-}
-
-void intel_fbdev_fini(struct drm_i915_private *dev_priv)
-{
-	struct intel_fbdev *ifbdev = fetch_and_zero(&dev_priv->display.fbdev.fbdev);
-
-	if (!ifbdev)
-		return;
-
-	intel_fbdev_destroy(ifbdev);
 }
 
 struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev *fbdev)

drivers/gpu/drm/i915/display/intel_fbdev.h

@@ -14,27 +14,11 @@ struct intel_fbdev;
 struct intel_framebuffer;
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
-int intel_fbdev_init(struct drm_device *dev);
-void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv);
-void intel_fbdev_unregister(struct drm_i915_private *dev_priv);
-void intel_fbdev_fini(struct drm_i915_private *dev_priv);
+void intel_fbdev_setup(struct drm_i915_private *dev_priv);
 void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous);
 struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev *fbdev);
 #else
-static inline int intel_fbdev_init(struct drm_device *dev)
-{
-	return 0;
-}
-
-static inline void intel_fbdev_initial_config_async(struct drm_i915_private *dev_priv)
-{
-}
-
-static inline void intel_fbdev_unregister(struct drm_i915_private *dev_priv)
-{
-}
-
-static inline void intel_fbdev_fini(struct drm_i915_private *dev_priv)
+static inline void intel_fbdev_setup(struct drm_i915_private *dev_priv)
 {
 }