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From: Huacai Chen <chenhuacai@loongson.cn>
To: Daniel Vetter <daniel.vetter@ffwll.ch>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Javier Martinez Canillas <javierm@redhat.com>
Cc: dri-devel@lists.freedesktop.org, Huacai Chen <chenhuacai@loongson.cn>
Subject: [PATCH V2] drivers/firmware: Move sysfb_init() from device_initcall to subsys_initcall_sync
Date: Sat,  2 Jul 2022 17:04:16 +0800	[thread overview]
Message-ID: <20220702090416.1217209-1-chenhuacai@loongson.cn> (raw)

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 [1].

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).

[1] https://lore.kernel.org/all/20220607182338.344270-1-javierm@redhat.com/

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
V2: Update commit messages.

 drivers/firmware/sysfb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
index 2bfbb05f7d89..aecf91517e54 100644
--- a/drivers/firmware/sysfb.c
+++ b/drivers/firmware/sysfb.c
@@ -80,4 +80,4 @@ static __init int sysfb_init(void)
 }
 
 /* must execute after PCI subsystem for EFI quirks */
-device_initcall(sysfb_init);
+subsys_initcall_sync(sysfb_init);
-- 
2.27.0


             reply	other threads:[~2022-07-02  9:03 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-02  9:04 Huacai Chen [this message]
2022-07-02 11:05 ` Javier Martinez Canillas
2022-07-04  1:09   ` Huacai Chen

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