video/aperture: Provide a VGA helper for gma500 and internal use

The hardware for gma500 is different from the rest, as it uses stolen
framebuffer memory that is not available via PCI BAR. The regular PCI
removal helper cannot detect the framebuffer, while the non-PCI helper
misses possible conflicting VGA devices (i.e., a framebuffer or text
console).

Gma500 therefore calls both helpers to catch all cases. It's confusing
as it implies that there's something about the PCI device that requires
ownership management. The relationship between the PCI device and the
VGA devices is non-obvious. At worst, readers might assume that calling
two functions for clearing aperture ownership is a bug in the driver.

Hence, move the PCI removal helper's code for VGA functionality into
a separate function and call this function from gma500. Documents the
purpose of each call to aperture helpers. The change contains comments
and example code form the discussion at [1].

v5:
	* fix grammar in gma500 comment (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20230404201842.567344-1-daniel.vetter@ffwll.ch/ # 1
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230406132109.32050-10-tzimmermann@suse.de

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/aperture.h b/include/linux/aperture.h
index 7248727753be..1a9a88b11584 100644
--- a/include/linux/aperture.h
+++ b/include/linux/aperture.h
@@ -16,6 +16,8 @@ int devm_aperture_acquire_for_platform_device(struct platform_device *pdev,
 int aperture_remove_conflicting_devices(resource_size_t base, resource_size_t size,
 					const char *name);
 
+int __aperture_remove_legacy_vga_devices(struct pci_dev *pdev);
+
 int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name);
 #else
 static inline int devm_aperture_acquire_for_platform_device(struct platform_device *pdev,
@@ -31,6 +33,11 @@ static inline int aperture_remove_conflicting_devices(resource_size_t base, reso
 	return 0;
 }
 
+static inline int __aperture_remove_legacy_vga_devices(struct pci_dev *pdev)
+{
+	return 0;
+}
+
 static inline int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name)
 {
 	return 0;