From 0c6b24d70da21201ed009a2aca740d2dfddc7ab5 Mon Sep 17 00:00:00 2001 From: Jason-JH Lin Date: Mon, 28 Jul 2025 10:48:50 +0800 Subject: [PATCH 1/4] drm/mediatek: Add error handling for old state CRTC in atomic_disable Introduce error handling to address an issue where, after a hotplug event, the cursor continues to update. This situation can lead to a kernel panic due to accessing the NULL `old_state->crtc`. E,g. Unable to handle kernel NULL pointer dereference at virtual address Call trace: mtk_crtc_plane_disable+0x24/0x140 mtk_plane_atomic_update+0x8c/0xa8 drm_atomic_helper_commit_planes+0x114/0x2c8 drm_atomic_helper_commit_tail_rpm+0x4c/0x158 commit_tail+0xa0/0x168 drm_atomic_helper_commit+0x110/0x120 drm_atomic_commit+0x8c/0xe0 drm_atomic_helper_update_plane+0xd4/0x128 __setplane_atomic+0xcc/0x110 drm_mode_cursor_common+0x250/0x440 drm_mode_cursor_ioctl+0x44/0x70 drm_ioctl+0x264/0x5d8 __arm64_sys_ioctl+0xd8/0x510 invoke_syscall+0x6c/0xe0 do_el0_svc+0x68/0xe8 el0_svc+0x34/0x60 el0t_64_sync_handler+0x1c/0xf8 el0t_64_sync+0x180/0x188 Adding NULL pointer checks to ensure stability by preventing operations on an invalid CRTC state. Fixes: d208261e9f7c ("drm/mediatek: Add wait_event_timeout when disabling plane") Signed-off-by: Jason-JH Lin Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20250728025036.24953-1-jason-jh.lin@mediatek.com/ Signed-off-by: Chun-Kuang Hu --- drivers/gpu/drm/mediatek/mtk_plane.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/mediatek/mtk_plane.c b/drivers/gpu/drm/mediatek/mtk_plane.c index cbc4f37da8ba..02349bd44001 100644 --- a/drivers/gpu/drm/mediatek/mtk_plane.c +++ b/drivers/gpu/drm/mediatek/mtk_plane.c @@ -292,7 +292,8 @@ static void mtk_plane_atomic_disable(struct drm_plane *plane, wmb(); /* Make sure the above parameter is set before update */ mtk_plane_state->pending.dirty = true; - mtk_crtc_plane_disable(old_state->crtc, plane); + if (old_state && old_state->crtc) + mtk_crtc_plane_disable(old_state->crtc, plane); } static void mtk_plane_atomic_update(struct drm_plane *plane, From f5b1819193667bf62c3c99d3921b9429997a14b2 Mon Sep 17 00:00:00 2001 From: Louis-Alexis Eyraud Date: Tue, 1 Jul 2025 09:30:40 +0200 Subject: [PATCH 2/4] drm/mediatek: dsi: Fix DSI host and panel bridge pre-enable order Since commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable"), the bridge pre_enable callbacks are now called before crtc enable, and the bridge post_disable callbacks after the crtc disable. In the mediatek-drm driver, this change leads to transfer errors on mtk_dsi_host_transfer callback processing during the panel bridge pre-enable sequence because the DSI host bridge pre_enable and CRTC enable sequences, that are enabling the required clocks and PHY using mtk_dsi_poweron function, are called after. So, in order to fix this call order issue, request the DSI host bridge be pre-enabled before panel bridge by setting pre_enable_prev_first flag on DSI device bridge in the mtk_dsi_host_attach function. Fixes: c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") Signed-off-by: Louis-Alexis Eyraud Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20250701-mediatek-drm-fix-dsi-panel-init-v1-1-7af4adb9fdeb@collabora.com/ Signed-off-by: Chun-Kuang Hu --- drivers/gpu/drm/mediatek/mtk_dsi.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index d7726091819c..0e2bcd5f67b7 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -1002,6 +1002,12 @@ static int mtk_dsi_host_attach(struct mipi_dsi_host *host, return PTR_ERR(dsi->next_bridge); } + /* + * set flag to request the DSI host bridge be pre-enabled before device bridge + * in the chain, so the DSI host is ready when the device bridge is pre-enabled + */ + dsi->next_bridge->pre_enable_prev_first = true; + drm_bridge_add(&dsi->bridge); ret = component_add(host->dev, &mtk_dsi_component_ops); From 1f403699c40f0806a707a9a6eed3b8904224021a Mon Sep 17 00:00:00 2001 From: Ma Ke Date: Tue, 12 Aug 2025 15:19:32 +0800 Subject: [PATCH 3/4] drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv Using device_find_child() and of_find_device_by_node() to locate devices could cause an imbalance in the device's reference count. device_find_child() and of_find_device_by_node() both call get_device() to increment the reference count of the found device before returning the pointer. In mtk_drm_get_all_drm_priv(), these references are never released through put_device(), resulting in permanent reference count increments. Additionally, the for_each_child_of_node() iterator fails to release node references in all code paths. This leaks device node references when loop termination occurs before reaching MAX_CRTC. These reference count leaks may prevent device/node resources from being properly released during driver unbind operations. As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'. Cc: stable@vger.kernel.org Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support") Signed-off-by: Ma Ke Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20250812071932.471730-1-make24@iscas.ac.cn/ Signed-off-by: Chun-Kuang Hu --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index d5e6bab36414..f8a817689e16 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -387,19 +387,19 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev) of_id = of_match_node(mtk_drm_of_ids, node); if (!of_id) - continue; + goto next_put_node; pdev = of_find_device_by_node(node); if (!pdev) - continue; + goto next_put_node; drm_dev = device_find_child(&pdev->dev, NULL, mtk_drm_match); if (!drm_dev) - continue; + goto next_put_device_pdev_dev; temp_drm_priv = dev_get_drvdata(drm_dev); if (!temp_drm_priv) - continue; + goto next_put_device_drm_dev; if (temp_drm_priv->data->main_len) all_drm_priv[CRTC_MAIN] = temp_drm_priv; @@ -411,10 +411,17 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev) if (temp_drm_priv->mtk_drm_bound) cnt++; - if (cnt == MAX_CRTC) { - of_node_put(node); +next_put_device_drm_dev: + put_device(drm_dev); + +next_put_device_pdev_dev: + put_device(&pdev->dev); + +next_put_node: + of_node_put(node); + + if (cnt == MAX_CRTC) break; - } } if (drm_priv->data->mmsys_dev_num == cnt) { From c34414883f773412964404d77cd2fea04c6f7d60 Mon Sep 17 00:00:00 2001 From: Louis-Alexis Eyraud Date: Mon, 18 Aug 2025 16:17:52 +0200 Subject: [PATCH 4/4] drm/mediatek: mtk_hdmi: Fix inverted parameters in some regmap_update_bits calls In mtk_hdmi driver, a recent change replaced custom register access function calls by regmap ones, but two replacements by regmap_update_bits were done incorrectly, because original offset and mask parameters were inverted, so fix them. Fixes: d6e25b3590a0 ("drm/mediatek: hdmi: Use regmap instead of iomem for main registers") Signed-off-by: Louis-Alexis Eyraud Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20250818-mt8173-fix-hdmi-issue-v1-1-55aff9b0295d@collabora.com/ Signed-off-by: Chun-Kuang Hu --- drivers/gpu/drm/mediatek/mtk_hdmi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c index 845fd8aa43c3..b766dd5e6c8d 100644 --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c @@ -182,8 +182,8 @@ static inline struct mtk_hdmi *hdmi_ctx_from_bridge(struct drm_bridge *b) static void mtk_hdmi_hw_vid_black(struct mtk_hdmi *hdmi, bool black) { - regmap_update_bits(hdmi->regs, VIDEO_SOURCE_SEL, - VIDEO_CFG_4, black ? GEN_RGB : NORMAL_PATH); + regmap_update_bits(hdmi->regs, VIDEO_CFG_4, + VIDEO_SOURCE_SEL, black ? GEN_RGB : NORMAL_PATH); } static void mtk_hdmi_hw_make_reg_writable(struct mtk_hdmi *hdmi, bool enable) @@ -310,8 +310,8 @@ static void mtk_hdmi_hw_send_info_frame(struct mtk_hdmi *hdmi, u8 *buffer, static void mtk_hdmi_hw_send_aud_packet(struct mtk_hdmi *hdmi, bool enable) { - regmap_update_bits(hdmi->regs, AUDIO_PACKET_OFF, - GRL_SHIFT_R2, enable ? 0 : AUDIO_PACKET_OFF); + regmap_update_bits(hdmi->regs, GRL_SHIFT_R2, + AUDIO_PACKET_OFF, enable ? 0 : AUDIO_PACKET_OFF); } static void mtk_hdmi_hw_config_sys(struct mtk_hdmi *hdmi)