Re: [PATCH RFC] drm/mediatek: Remove all conflicting aperture devices during probe
From: Chen-Yu Tsai <wenst@chromium.org>
Date: 2026-02-10 09:55:09
Also in:
dri-devel, linux-mediatek, lkml
On Tue, Feb 10, 2026 at 5:34 PM Luca Leonardo Scorcia [off-list ref] wrote:
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 as we probe 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. Signed-off-by: Luca Leonardo Scorcia <redacted> --- This patch has been tested on Xiaomi Mi Smart Clock, however I'd like to get some feedback from more knowledgeable people, especially about those points: 1. Is aperture support on mtk-drm desired at all? 2. mtk-drm does not know about the fb address therefore as far as I can see we can't use the more specific function aperture_remove_conflicting_devices. This means that all generic aperture drivers will be unloaded. It might not be a real world issue as I can't see why one might want to load mtk-drm while keeping other aperture device drivers active, but my experience is very limited.
This is pretty much what all other platform drivers do. So that's fine.
quoted hunk ↗ jump to hunk
Thanks! drivers/gpu/drm/mediatek/mtk_drm_drv.c | 6 ++++++ 1 file changed, 6 insertions(+)diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index a94c51a83261..17e45b93fe49 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>@@ -1116,6 +1117,11 @@ static int mtk_drm_probe(struct platform_device *pdev) if (!private->all_drm_private) return -ENOMEM; + /* Remove framebuffer owners, this will release fbcon if active */ + ret = aperture_remove_all_conflicting_devices(DRIVER_NAME); + if (ret < 0) + dev_err(dev, "Failed to remove conflicting aperture devices (%d)", ret); +
I believe this could be in mtk_drm_bind() just before drm_dev_register(). The idea is you want to kick out the existing framebuffer as late as possible to reduce the time the screen is unresponsive. ChenYu
/* Bringup ovl_adaptor */
if (mtk_drm_find_mmsys_comp(private, DDP_COMPONENT_DRM_OVL_ADAPTOR)) {
ovl_adaptor = platform_device_register_data(dev, "mediatek-disp-ovl-adaptor",
--
2.43.0