linux-kernel - [PATCH] drm/rockchip: remove early framebuffers before registering the fbdev

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Message-Id: <20210515221447.429779-1-javierm@redhat.com>
Date:   Sun, 16 May 2021 00:14:47 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Javier Martinez Canillas <javierm@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Heiko Stübner <heiko@...ech.de>,
        Peter Robinson <pbrobinson@...il.com>,
        Sandy Huang <hjc@...k-chips.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: [PATCH] drm/rockchip: remove early framebuffers before registering the fbdev

There are drivers that register framebuffer devices very early in the boot
process and make use of the existing framebuffer as setup by the firmware.

If one of those drivers has registered a fbdev, then the fbdev registered
by a DRM driver won't be bound to the framebuffer console. To avoid that,
remove any early framebuffer before registering a DRM framebuffer device.

By doing that, the fb mapped to the console is switched correctly from the
early fbdev to the one registered by the rockchip DRM driver:

    [   40.752420] fb0: switching to rockchip-drm-fb from EFI VGA

Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

 drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c b/drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c
index 2fdc455c4ad..e3e5b63fdcc 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c
@@ -4,6 +4,7 @@
  * Author:Mark Yao <mark.yao@...k-chips.com>
  */
 
+#include <drm/drm_aperture.h>
 #include <drm/drm.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
@@ -124,6 +125,15 @@ int rockchip_drm_fbdev_init(struct drm_device *dev)
 
 	drm_fb_helper_prepare(dev, helper, &rockchip_drm_fb_helper_funcs);
 
+	/* Remove early framebuffers (e.g: simplefb or efifb) */
+	ret = drm_aperture_remove_framebuffers(false, "rockchip-drm-fb");
+	if (ret) {
+		DRM_DEV_ERROR(dev->dev,
+			      "Failed to remove early framebuffers - %d.\n",
+			      ret);
+		return ret;
+	}
+
 	ret = drm_fb_helper_init(dev, helper);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dev->dev,
-- 
2.31.1