linux-kernel - [PATCH v2 5/5] Revert "fbdev: Prevent probing generic drivers if a FB is already registered"

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Date:   Fri,  8 Apr 2022 18:13:22 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel@...ts.freedesktop.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Zack Rusin <zackr@...are.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Ilya Trukhanov <lahvuun@...il.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Peter Jones <pjones@...hat.com>, linux-fbdev@...r.kernel.org,
        Helge Deller <deller@....de>
Subject: [PATCH v2 5/5] Revert "fbdev: Prevent probing generic drivers if a FB is already registered"

From: Daniel Vetter <daniel.vetter@...ll.ch>

This reverts commit fb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee.

With

commit 27599aacbaefcbf2af7b06b0029459bbf682000d
Author: Thomas Zimmermann <tzimmermann@...e.de>
Date:   Tue Jan 25 10:12:18 2022 +0100

    fbdev: Hot-unplug firmware fb devices on forced removal

this should be fixed properly and we can remove this somewhat hackish
check here (e.g. this won't catch drm drivers if fbdev emulation isn't
enabled).

Cc: Thomas Zimmermann <tzimmermann@...e.de>
Cc: Zack Rusin <zackr@...are.com>
Cc: Javier Martinez Canillas <javierm@...hat.com>
Cc: Zack Rusin <zackr@...are.com>
Cc: Hans de Goede <hdegoede@...hat.com>
Cc: Ilya Trukhanov <lahvuun@...il.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
Cc: Peter Jones <pjones@...hat.com>
Cc: linux-fbdev@...r.kernel.org
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

(no changes since v1)

 drivers/video/fbdev/efifb.c    | 11 -----------
 drivers/video/fbdev/simplefb.c | 11 -----------
 2 files changed, 22 deletions(-)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index ea42ba6445b2..edca3703b964 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -351,17 +351,6 @@ static int efifb_probe(struct platform_device *dev)
 	char *option = NULL;
 	efi_memory_desc_t md;
 
-	/*
-	 * Generic drivers must not be registered if a framebuffer exists.
-	 * If a native driver was probed, the display hardware was already
-	 * taken and attempting to use the system framebuffer is dangerous.
-	 */
-	if (num_registered_fb > 0) {
-		dev_err(&dev->dev,
-			"efifb: a framebuffer is already registered\n");
-		return -EINVAL;
-	}
-
 	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
 		return -ENODEV;
 
diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 94fc9c6d0411..0ef41173325a 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -413,17 +413,6 @@ static int simplefb_probe(struct platform_device *pdev)
 	struct simplefb_par *par;
 	struct resource *res, *mem;
 
-	/*
-	 * Generic drivers must not be registered if a framebuffer exists.
-	 * If a native driver was probed, the display hardware was already
-	 * taken and attempting to use the system framebuffer is dangerous.
-	 */
-	if (num_registered_fb > 0) {
-		dev_err(&pdev->dev,
-			"simplefb: a framebuffer is already registered\n");
-		return -EINVAL;
-	}
-
 	if (fb_get_options("simplefb", NULL))
 		return -ENODEV;
 
-- 
2.35.1