Re: [PATCH v2] drm/mediatek: Remove all conflicting aperture devices during probe

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

On Thu, 2026-02-12 at 19:22 +0000, Luca Leonardo Scorcia wrote:
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> 
> 
> If a device has a framebuffer available it might be already used as
> display by simple-framebuffer or simpledrm when mediatek-drm is probed.
> This is actually helpful when porting to a new device as
> framebuffers are simple to setup in device trees and fbcon can be
> used to monitor the kernel boot process.
> 
> When drm-mediatek loads a new fb device is initialized, however
> fbcon remains attached to the initial framebuffer which is no longer
> connected to the actual display - the early fb is never removed.
> 
> We can gracefully transition from framebuffer handling to drm-managed
> display by calling aperture_remove_all_conflicting_devices before
> registering mediatek-drm. This takes care of unloading other fb
> devices/drivers and disconnects fbcon which then automatically
> reconnects to mediatekdrmfb as soon as it's available.
> 
> The function is invoked just before drm_dev_register() to kick out
> the existing framebuffer as late as possible to reduce the time the
> screen is unresponsive.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: Luca Leonardo Scorcia <l.scorcia@gmail.com>
> ---
> v2: Moved the call to aperture_remove_all_conflicting_devices to
>     right before drm_dev_register()
> 
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> index a94c51a83261..02effd9fc698 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> @@ -4,6 +4,7 @@
>   * Author: YT SHEN <yt.shen@mediatek.com>
>   */
> 
> +#include <linux/aperture.h>
>  #include <linux/component.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> @@ -670,6 +671,10 @@ static int mtk_drm_bind(struct device *dev)
>         if (ret < 0)
>                 goto err_free;
> 
> +       ret = aperture_remove_all_conflicting_devices(DRIVER_NAME);
> +       if (ret < 0)
> +               dev_err(dev, "Error %d while removing conflicting aperture devices", ret);
> +
>         ret = drm_dev_register(drm, 0);
>         if (ret < 0)
>                 goto err_deinit;
> --
> 2.43.0
> 
>