[PATCH] drm/bridge: analogix: protect power when get_modes or detect

[Mark Yao]

The drm callback ->detect and ->get_modes seems is not power safe,
they may be called when device is power off, do register access on
detect or get_modes will cause system die.

Here is the path call ->detect before analogix_dp power on
[<ffffff800843babc>] analogix_dp_detect+0x44/0xdc
[<ffffff80083fd840>] 
drm_helper_probe_single_connector_modes_merge_bits+0xe8/0x41c
[<ffffff80083fdb84>] drm_helper_probe_single_connector_modes+0x10/0x18
[<ffffff8008418d24>] drm_mode_getconnector+0xf4/0x304
[<ffffff800840cff0>] drm_ioctl+0x23c/0x390
[<ffffff80081a8adc>] do_vfs_ioctl+0x4b8/0x58c
[<ffffff80081a8c10>] SyS_ioctl+0x60/0x88

Cc: Inki Dae <inki....@samsung.com>
Cc: Sean Paul <seanp...@chromium.org>
Cc: Gustavo Padovan <gustavo.pado...@collabora.co.uk>
Cc: "Ville Syrjälä" <ville.syrj...@linux.intel.com>

Signed-off-by: Mark Yao <mark....@rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index efac8ab..09dece2 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1062,6 +1062,13 @@ int analogix_dp_get_modes(struct drm_connector 
*connector)
                return 0;
        }
 
+       if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+               pm_runtime_get_sync(dp->dev);
+
+               if (dp->plat_data->power_on)
+                       dp->plat_data->power_on(dp->plat_data);
+       }
+
        if (analogix_dp_handle_edid(dp) == 0) {
                drm_mode_connector_update_edid_property(&dp->connector, edid);
                num_modes += drm_add_edid_modes(&dp->connector, edid);
@@ -1073,6 +1080,13 @@ int analogix_dp_get_modes(struct drm_connector 
*connector)
        if (dp->plat_data->get_modes)
                num_modes += dp->plat_data->get_modes(dp->plat_data, connector);
 
+       if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+               if (dp->plat_data->power_off)
+                       dp->plat_data->power_off(dp->plat_data);
+
+               pm_runtime_put_sync(dp->dev);
+       }
+
        ret = analogix_dp_prepare_panel(dp, false, false);
        if (ret)
                DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
@@ -1106,9 +1120,23 @@ analogix_dp_detect(struct drm_connector *connector, bool 
force)
                return connector_status_disconnected;
        }
 
+       if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+               pm_runtime_get_sync(dp->dev);
+
+               if (dp->plat_data->power_on)
+                       dp->plat_data->power_on(dp->plat_data);
+       }
+
        if (!analogix_dp_detect_hpd(dp))
                status = connector_status_connected;
 
+       if (dp->dpms_mode != DRM_MODE_DPMS_ON) {
+               if (dp->plat_data->power_off)
+                       dp->plat_data->power_off(dp->plat_data);
+
+               pm_runtime_put_sync(dp->dev);
+       }
+
        ret = analogix_dp_prepare_panel(dp, false, false);
        if (ret)
                DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
-- 
1.9.1