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

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

[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 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@redhat.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@rock-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


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Re: [PATCH] drm/rockchip: remove early framebuffers before registering the fbdev

[Thomas Zimmermann]

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Hi

Am 16.05.21 um 00:14 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 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@redhat.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@rock-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;
> +	}
> +

Such code used to be part of the fbdev helpers, but it's not really 
related to fbdev functonality. Rather it controls ownership of the I/O 
ranges.

This code block should be done at the very beginning; before the driver 
tries to reserve the device's I/O ranges. Probably at [1]

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/v5.13-rc1/source/drivers/gpu/drm/rockchip/rockchip_drm_drv.c#L116


>   	ret = drm_fb_helper_init(dev, helper);
>   	if (ret < 0) {
>   		DRM_DEV_ERROR(dev->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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