[PATCH 6.1.y-cip 3/7] drm: renesas: rz-du: mipi_dsi: fix kernel panic when rebooting for some panels

Chris Brandt
2026-04-13T17:18:44Z

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

commit 64aa8b3a60a825134f7d866adf05c024bbe0c24c upstream.

Since commit 56de5e305d4b ("clk: renesas: r9a07g044: Add MSTOP for RZ/G2L")
we may get the following kernel panic, for some panels, when rebooting:

systemd-shutdown[1]: Rebooting.
Call trace:
...
do_serror+0x28/0x68
el1h_64_error_handler+0x34/0x50
el1h_64_error+0x6c/0x70
rzg2l_mipi_dsi_host_transfer+0x114/0x458 (P)
mipi_dsi_device_transfer+0x44/0x58
mipi_dsi_dcs_set_display_off_multi+0x9c/0xc4
ili9881c_unprepare+0x38/0x88
drm_panel_unprepare+0xbc/0x108

This happens for panels that need to send MIPI-DSI commands in their
unprepare() callback. Since the MIPI-DSI interface is stopped at that
point, rzg2l_mipi_dsi_host_transfer() triggers the kernel panic.

Fix by moving rzg2l_mipi_dsi_stop() to new callback function
rzg2l_mipi_dsi_atomic_post_disable().

With this change we now have the correct power-down/stop sequence:

systemd-shutdown[1]: Rebooting.
rzg2l-mipi-dsi 10850000.dsi: rzg2l_mipi_dsi_atomic_disable(): entry
ili9881c-dsi 10850000.dsi.0: ili9881c_unprepare(): entry
rzg2l-mipi-dsi 10850000.dsi: rzg2l_mipi_dsi_atomic_post_disable(): entry
reboot: Restarting system

Suggested-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20260112154333.655352-1-hugo@hugovil.com
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
---
drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
index 4ee784f66037..d3aae2501b9e 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -1069,6 +1069,13 @@ static void rzg2l_mipi_dsi_atomic_disable(struct drm_bridge *bridge,

rzg2l_mipi_dsi_stop_video(dsi);
rzg2l_mipi_dsi_stop_hs_clock(dsi);
+}
+
+static void rzg2l_mipi_dsi_atomic_post_disable(struct drm_bridge *bridge,
+ struct drm_bridge_state *old_bridge_state)
+{
+ struct rzg2l_mipi_dsi *dsi = bridge_to_rzg2l_mipi_dsi(bridge);
+
rzg2l_mipi_dsi_stop(dsi);
}

@@ -1104,6 +1111,7 @@ static const struct drm_bridge_funcs rzg2l_mipi_dsi_bridge_ops = {
.atomic_pre_enable = rzg2l_mipi_dsi_atomic_pre_enable,
.atomic_enable = rzg2l_mipi_dsi_atomic_enable,
.atomic_disable = rzg2l_mipi_dsi_atomic_disable,
+ .atomic_post_disable = rzg2l_mipi_dsi_atomic_post_disable,
.mode_valid = rzg2l_mipi_dsi_bridge_mode_valid,
};

--
2.52.0