[PATCH v2 1/3] drm/i915: Allow switching away via vga-switcheroo if uninitialized

[Thomas Zimmermann]

Always allow switching away via vga-switcheroo if the display is
uninitalized. Instead prevent switching to i915 if the device has
not been initialized.

This issue was introduced by commit 5df7bd130818 ("drm/i915: skip
display initialization when there is no display") protected, which
protects code paths from being executed on uninitialized devices.
In the case of vga-switcheroo, we want to allow a switch away from
i915's device. So run vga_switcheroo_process_delayed_switch() and
test in the switcheroo callbacks if the i915 device is available.

Fixes: 5df7bd130818 ("drm/i915: skip display initialization when there is no display")
Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: "Ville Syrjälä" <ville.syrjala at linux.intel.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
Cc: Imre Deak <imre.deak at intel.com>
Cc: "Jouni Högander" <jouni.hogander at intel.com>
Cc: Uma Shankar <uma.shankar at intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
Cc: "Jason A. Donenfeld" <Jason at zx2c4.com>
Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: Ramalingam C <ramalingam.c at intel.com>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Andi Shyti <andi.shyti at linux.intel.com>
Cc: Andrzej Hajda <andrzej.hajda at intel.com>
Cc: "José Roberto de Souza" <jose.souza at intel.com>
Cc: Julia Lawall <Julia.Lawall at inria.fr>
Cc: intel-gfx at lists.freedesktop.org
Cc: <stable at vger.kernel.org> # v5.14+
---
 drivers/gpu/drm/i915/i915_driver.c     | 3 +--
 drivers/gpu/drm/i915/i915_switcheroo.c | 6 +++++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index c1e427ba57ae..33e231b120c1 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -1075,8 +1075,7 @@ static void i915_driver_lastclose(struct drm_device *dev)
 
 	intel_fbdev_restore_mode(dev);
 
-	if (HAS_DISPLAY(i915))
-		vga_switcheroo_process_delayed_switch();
+	vga_switcheroo_process_delayed_switch();
 }
 
 static void i915_driver_postclose(struct drm_device *dev, struct drm_file *file)
diff --git a/drivers/gpu/drm/i915/i915_switcheroo.c b/drivers/gpu/drm/i915/i915_switcheroo.c
index 23777d500cdf..f45bd6b6cede 100644
--- a/drivers/gpu/drm/i915/i915_switcheroo.c
+++ b/drivers/gpu/drm/i915/i915_switcheroo.c
@@ -19,6 +19,10 @@ static void i915_switcheroo_set_state(struct pci_dev *pdev,
 		dev_err(&pdev->dev, "DRM not initialized, aborting switch.\n");
 		return;
 	}
+	if (!HAS_DISPLAY(i915)) {
+		dev_err(&pdev->dev, "Device state not initialized, aborting switch.\n");
+		return;
+	}
 
 	if (state == VGA_SWITCHEROO_ON) {
 		drm_info(&i915->drm, "switched on\n");
@@ -44,7 +48,7 @@ static bool i915_switcheroo_can_switch(struct pci_dev *pdev)
 	 * locking inversion with the driver load path. And the access here is
 	 * completely racy anyway. So don't bother with locking for now.
 	 */
-	return i915 && atomic_read(&i915->drm.open_count) == 0;
+	return i915 && HAS_DISPLAY(i915) && atomic_read(&i915->drm.open_count) == 0;
 }
 
 static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
-- 
2.39.0