Re: [PATCH v2] drm/rockchip: remove existing generic drivers to take over the device

From: Thomas Zimmermann
Date: Sun May 16 2021 - 06:30:56 EST

Am 16.05.21 um 09:48 schrieb Javier Martinez Canillas:
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 fallback fbdev
the DRM driver won't be bound to the framebuffer console. To avoid that,
remove any existing generic driver and take over the graphics 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@xxxxxxxxxx>

Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

Ping me if no one else merges the patch.

Best regards


Changes in v2:
- Move drm_aperture_remove_framebuffers() call to .bind callback (tzimmermann).
- Adapt subject line, commit message, etc accordingly.

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

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index 212bd87c0c4..b730b8d5d94 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -16,6 +16,7 @@
#include <linux/console.h>
#include <linux/iommu.h>
+#include <drm/drm_aperture.h>
#include <drm/drm_drv.h>
#include <drm/drm_fb_helper.h>
#include <drm/drm_gem_cma_helper.h>
@@ -114,6 +115,15 @@ static int rockchip_drm_bind(struct device *dev)
struct rockchip_drm_private *private;
int ret;
+ /* Remove existing drivers that may own the framebuffer memory. */
+ ret = drm_aperture_remove_framebuffers(false, "rockchip-drm-fb");
+ if (ret) {
+ "Failed to remove existing framebuffers - %d.\n",
+ ret);
+ return ret;
+ }
drm_dev = drm_dev_alloc(&rockchip_drm_driver, dev);
if (IS_ERR(drm_dev))
return PTR_ERR(drm_dev);

Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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