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603dc7ed91
Fbdev's helpers for handling conflicting framebuffer drivers are related to framebuffer apertures, not console emulation. Therefore remove them from drm_fb_helper.h and inline them into the aperture helpers. No functional changes. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210412131043.5787-4-tzimmermann@suse.de
131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
// SPDX-License-Identifier: MIT
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#include <linux/fb.h>
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#include <linux/vgaarb.h>
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#include <drm/drm_aperture.h>
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/**
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* DOC: overview
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*
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* A graphics device might be supported by different drivers, but only one
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* driver can be active at any given time. Many systems load a generic
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* graphics drivers, such as EFI-GOP or VESA, early during the boot process.
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* During later boot stages, they replace the generic driver with a dedicated,
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* hardware-specific driver. To take over the device the dedicated driver
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* first has to remove the generic driver. DRM aperture functions manage
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* ownership of DRM framebuffer memory and hand-over between drivers.
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*
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* DRM drivers should call drm_aperture_remove_conflicting_framebuffers()
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* at the top of their probe function. The function removes any generic
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* driver that is currently associated with the given framebuffer memory.
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* If the framebuffer is located at PCI BAR 0, the rsp code looks as in the
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* example given below.
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*
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* .. code-block:: c
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*
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* static int remove_conflicting_framebuffers(struct pci_dev *pdev)
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* {
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* bool primary = false;
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* resource_size_t base, size;
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* int ret;
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*
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* base = pci_resource_start(pdev, 0);
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* size = pci_resource_len(pdev, 0);
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* #ifdef CONFIG_X86
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* primary = pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW;
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* #endif
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*
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* return drm_aperture_remove_conflicting_framebuffers(base, size, primary,
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* "example driver");
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* }
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*
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* static int probe(struct pci_dev *pdev)
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* {
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* int ret;
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*
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* // Remove any generic drivers...
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* ret = remove_conflicting_framebuffers(pdev);
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* if (ret)
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* return ret;
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*
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* // ... and initialize the hardware.
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* ...
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*
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* drm_dev_register();
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*
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* return 0;
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* }
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*
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* PCI device drivers should call
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* drm_aperture_remove_conflicting_pci_framebuffers() and let it detect the
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* framebuffer apertures automatically. Device drivers without knowledge of
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* the framebuffer's location shall call drm_aperture_remove_framebuffers(),
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* which removes all drivers for known framebuffer.
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*/
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/**
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* drm_aperture_remove_conflicting_framebuffers - remove existing framebuffers in the given range
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* @base: the aperture's base address in physical memory
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* @size: aperture size in bytes
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* @primary: also kick vga16fb if present
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* @name: requesting driver name
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*
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* This function removes graphics device drivers which use memory range described by
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* @base and @size.
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*
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* Returns:
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* 0 on success, or a negative errno code otherwise
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*/
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int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_size_t size,
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bool primary, const char *name)
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{
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#if IS_REACHABLE(CONFIG_FB)
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struct apertures_struct *a;
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int ret;
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a = alloc_apertures(1);
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if (!a)
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return -ENOMEM;
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a->ranges[0].base = base;
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a->ranges[0].size = size;
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ret = remove_conflicting_framebuffers(a, name, primary);
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kfree(a);
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return ret;
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#else
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return 0;
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#endif
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}
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EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers);
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/**
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* drm_aperture_remove_conflicting_pci_framebuffers - remove existing framebuffers for PCI devices
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* @pdev: PCI device
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* @name: requesting driver name
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*
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* This function removes graphics device drivers using memory range configured
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* for any of @pdev's memory bars. The function assumes that PCI device with
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* shadowed ROM drives a primary display and so kicks out vga16fb.
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*
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* Returns:
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* 0 on success, or a negative errno code otherwise
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*/
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int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const char *name)
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{
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int ret = 0;
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/*
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* WARNING: Apparently we must kick fbdev drivers before vgacon,
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* otherwise the vga fbdev driver falls over.
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*/
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#if IS_REACHABLE(CONFIG_FB)
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ret = remove_conflicting_pci_framebuffers(pdev, name);
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#endif
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if (ret == 0)
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ret = vga_remove_vgacon(pdev);
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return ret;
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}
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EXPORT_SYMBOL(drm_aperture_remove_conflicting_pci_framebuffers);
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