linux-kernel - [PATCH 1/2] drm/aperture: Split conflicting platform driver removal

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Date:   Mon, 06 Jun 2022 11:53:22 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch
Cc:     Laszlo Ersek <lersek@...hat.com>, Laszlo Ersek <lersek@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: [PATCH 1/2] drm/aperture: Split conflicting platform driver removal

Split the removal of platform drivers conflicting with PCI resources from
drm_aperture_remove_conflicting_pci_framebuffers() to support both non-DRM
callers and better modularity.  This is intended to support the vfio-pci
driver, which can acquire ownership of PCI graphics devices, but is not
itself a DRM or FB driver, and therefore has no Kconfig dependencies.  The
remaining actions of drm_aperture_remove_conflicting_pci_framebuffers() are
already exported from their respective subsystems, therefore this allows
vfio-pci to separate each set of conflicts independently based on the
configured features.

Reported-by: Laszlo Ersek <lersek@...hat.com>
Tested-by: Laszlo Ersek <lersek@...hat.com>
Suggested-by: Gerd Hoffmann <kraxel@...hat.com>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
 drivers/gpu/drm/drm_aperture.c |   33 ++++++++++++++++++++++++---------
 include/drm/drm_aperture.h     |    2 ++
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c
index 74bd4a76b253..5b2500f7fb8b 100644
--- a/drivers/gpu/drm/drm_aperture.c
+++ b/drivers/gpu/drm/drm_aperture.c
@@ -313,6 +313,28 @@ int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_
 }
 EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers);
 
+/**
+ * drm_aperture_detach_platform_drivers - detach platform drivers conflicting with PCI device
+ * @pdev: PCI device
+ *
+ * This function detaches platform drivers with resource conflicts to the memory
+ * bars of the provided @pdev.
+ */
+void drm_aperture_detach_platform_drivers(struct pci_dev *pdev)
+{
+	resource_size_t base, size;
+	int bar;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
+		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
+			continue;
+		base = pci_resource_start(pdev, bar);
+		size = pci_resource_len(pdev, bar);
+		drm_aperture_detach_drivers(base, size);
+	}
+}
+EXPORT_SYMBOL(drm_aperture_detach_platform_drivers);
+
 /**
  * drm_aperture_remove_conflicting_pci_framebuffers - remove existing framebuffers for PCI devices
  * @pdev: PCI device
@@ -328,16 +350,9 @@ EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers);
 int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
 						     const struct drm_driver *req_driver)
 {
-	resource_size_t base, size;
-	int bar, ret = 0;
+	int ret = 0;
 
-	for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
-		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
-			continue;
-		base = pci_resource_start(pdev, bar);
-		size = pci_resource_len(pdev, bar);
-		drm_aperture_detach_drivers(base, size);
-	}
+	drm_aperture_detach_platform_drivers(pdev);
 
 	/*
 	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
diff --git a/include/drm/drm_aperture.h b/include/drm/drm_aperture.h
index 7096703c3949..53fd36fa258e 100644
--- a/include/drm/drm_aperture.h
+++ b/include/drm/drm_aperture.h
@@ -15,6 +15,8 @@ int devm_aperture_acquire_from_firmware(struct drm_device *dev, resource_size_t
 int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_size_t size,
 						 bool primary, const struct drm_driver *req_driver);
 
+void drm_aperture_detach_platform_drivers(struct pci_dev *pdev);
+
 int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
 						     const struct drm_driver *req_driver);