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60aebc9559
Consider a configuration like this:
1, efifb (or simpledrm) is built-in;
2, a native display driver (such as radeon) is also built-in.
As Javier said, this is not a common configuration (the native display
driver is usually built as a module), but it can happen and cause some
trouble.
In this case, since efifb, radeon and sysfb are all in device_initcall()
level, the order in practise is like this:
efifb registered at first, but no "efi-framebuffer" device yet. radeon
registered later, and /dev/fb0 created. sysfb_init() comes at last, it
registers "efi-framebuffer" and then causes an error message "efifb: a
framebuffer is already registered". Make sysfb_init() to be subsys_
initcall_sync() can avoid this. And Javier Martinez Canillas is trying
to make a more general solution in commit 873eb3b118 ("fbdev: Disable
sysfb device registration when removing conflicting FBs").
However, this patch still makes sense because it can make the screen
display as early as possible (We cannot move to subsys_initcall, since
sysfb_init() should be executed after PCI enumeration).
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220704011704.1418055-1-chenhuacai@loongson.cn
131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Generic System Framebuffers
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* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
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*/
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/*
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* Simple-Framebuffer support
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* Create a platform-device for any available boot framebuffer. The
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* simple-framebuffer platform device is already available on DT systems, so
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* this module parses the global "screen_info" object and creates a suitable
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* platform device compatible with the "simple-framebuffer" DT object. If
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* the framebuffer is incompatible, we instead create a legacy
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* "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and
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* pass the screen_info as platform_data. This allows legacy drivers
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* to pick these devices up without messing with simple-framebuffer drivers.
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* The global "screen_info" is still valid at all times.
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*
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* If CONFIG_SYSFB_SIMPLEFB is not selected, never register "simple-framebuffer"
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* platform devices, but only use legacy framebuffer devices for
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* backwards compatibility.
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*
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* TODO: We set the dev_id field of all platform-devices to 0. This allows
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* other OF/DT parsers to create such devices, too. However, they must
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* start at offset 1 for this to work.
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*/
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/platform_data/simplefb.h>
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#include <linux/platform_device.h>
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#include <linux/screen_info.h>
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#include <linux/sysfb.h>
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static struct platform_device *pd;
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static DEFINE_MUTEX(disable_lock);
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static bool disabled;
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static bool sysfb_unregister(void)
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{
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if (IS_ERR_OR_NULL(pd))
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return false;
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platform_device_unregister(pd);
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pd = NULL;
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return true;
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}
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/**
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* sysfb_disable() - disable the Generic System Framebuffers support
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*
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* This disables the registration of system framebuffer devices that match the
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* generic drivers that make use of the system framebuffer set up by firmware.
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*
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* It also unregisters a device if this was already registered by sysfb_init().
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*
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* Context: The function can sleep. A @disable_lock mutex is acquired to serialize
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* against sysfb_init(), that registers a system framebuffer device.
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*/
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void sysfb_disable(void)
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{
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mutex_lock(&disable_lock);
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sysfb_unregister();
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disabled = true;
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mutex_unlock(&disable_lock);
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}
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EXPORT_SYMBOL_GPL(sysfb_disable);
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static __init int sysfb_init(void)
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{
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struct screen_info *si = &screen_info;
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struct simplefb_platform_data mode;
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const char *name;
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bool compatible;
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int ret = 0;
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mutex_lock(&disable_lock);
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if (disabled)
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goto unlock_mutex;
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sysfb_apply_efi_quirks();
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/* try to create a simple-framebuffer device */
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compatible = sysfb_parse_mode(si, &mode);
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if (compatible) {
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pd = sysfb_create_simplefb(si, &mode);
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if (!IS_ERR(pd))
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goto unlock_mutex;
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}
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/* if the FB is incompatible, create a legacy framebuffer device */
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if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
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name = "efi-framebuffer";
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else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
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name = "vesa-framebuffer";
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else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)
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name = "vga-framebuffer";
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else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)
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name = "ega-framebuffer";
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else
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name = "platform-framebuffer";
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pd = platform_device_alloc(name, 0);
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if (!pd) {
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ret = -ENOMEM;
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goto unlock_mutex;
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}
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sysfb_set_efifb_fwnode(pd);
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ret = platform_device_add_data(pd, si, sizeof(*si));
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if (ret)
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goto err;
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ret = platform_device_add(pd);
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if (ret)
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goto err;
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goto unlock_mutex;
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err:
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platform_device_put(pd);
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unlock_mutex:
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mutex_unlock(&disable_lock);
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return ret;
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}
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/* must execute after PCI subsystem for EFI quirks */
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subsys_initcall_sync(sysfb_init);
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