[Intel-gfx] [PATCH] drm/i915/dsi: unregister gmbus if LFP display was MIPI panel

[Lee Shawn C]

Gmbus driver would setup all Intel i2c GMBuses. But DDC bus
may configured as gpio and reserved for MIPI driver to control
panel power on/off sequence.

Using i2c tool to communicate to peripherals via i2c interface
reversed for gmbus(DDC). There will be some high/low pulse
appear on DDC SCL and SDA (might be host sent out i2c slave
address). MIPI panel would be impacted due to unexpected signal
then caused abnormal display or shut down issue.

Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni at intel.com>
Cc: Cooper Chiou <cooper.chiou at intel.com>
Cc: William Tseng <william.tseng at intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
---
 drivers/gpu/drm/i915/display/icl_dsi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
index 060bc8fb0d30..d2504e291fcb 100644
--- a/drivers/gpu/drm/i915/display/icl_dsi.c
+++ b/drivers/gpu/drm/i915/display/icl_dsi.c
@@ -1999,6 +1999,7 @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
 	struct intel_connector *intel_connector;
 	struct drm_connector *connector;
 	struct drm_display_mode *fixed_mode;
+	struct intel_gmbus *bus;
 	enum port port;
 
 	if (!intel_bios_is_dsi_present(dev_priv, &port))
@@ -2092,6 +2093,19 @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
 	icl_dphy_param_init(intel_dsi);
 
 	icl_dsi_add_properties(intel_connector);
+
+	/*
+	 * DDC bus may configured as gpio and reserved for MIPI driver
+	 * to control panel power on/off sequence. so, unregister gmbus
+	 * if MIPI was LFP display.
+	 */
+	bus = &dev_priv->gmbus[GMBUS_PIN_1_BXT];
+	i2c_del_adapter(&bus->adapter);
+
+	if (dev_priv->vbt.dsi.config->dual_link) {
+		bus = &dev_priv->gmbus[GMBUS_PIN_2_BXT];
+		i2c_del_adapter(&bus->adapter);
+	}
 	return;
 
 err:
-- 
2.31.1