[Intel-gfx] [PATCH 21/49] drm/i915/bxt: WARN in case BXT unused gmbus ports are accessed

[Imre Deak]

From: "A.Sunil Kamath" <sunil.kamath at intel.com>

This patch will WARN if unused gmbus ports gets accessed for
BXT using gmbus_get_adapter also ensure that only valid ports
of BXT gets used. For BXT its more important to do this as it
has only 3 valid ports and structure has empty content otherwise.

Because of additonal IS_BROXTON check an additional "dev"
argument is added to intel_gmbus_is_port_valid. Also added
related changes in other places from where this function is accessed.

v1: This WARN patch is added as per review comments from
Daniel Vetter on gmbus BXT patch

v2: Changed get_adapter to have only one is_port_valid call
according to review comments from M Satheeshakrishna.

v3: Early bail out on errors according to review comments from
Daniel Vetter.

Issue: VIZ-3574
Signed-off-by: A.Sunil Kamath <sunil.kamath at intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h   | 8 ++++++--
 drivers/gpu/drm/i915/intel_bios.c | 3 ++-
 drivers/gpu/drm/i915/intel_dvo.c  | 2 +-
 drivers/gpu/drm/i915/intel_i2c.c  | 9 ++++++---
 drivers/gpu/drm/i915/intel_lvds.c | 2 +-
 drivers/gpu/drm/i915/intel_sdvo.c | 4 +++-
 6 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8fb7cc0..52e5f18 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3037,9 +3037,13 @@ void i915_teardown_sysfs(struct drm_device *dev_priv);
 /* intel_i2c.c */
 extern int intel_setup_gmbus(struct drm_device *dev);
 extern void intel_teardown_gmbus(struct drm_device *dev);
-static inline bool intel_gmbus_is_port_valid(unsigned port)
+static inline bool
+intel_gmbus_is_port_valid(struct drm_device *dev, unsigned port)
 {
-	return (port >= GMBUS_PORT_SSC && port <= GMBUS_PORT_DPD);
+	if (IS_BROXTON(dev))
+		return port >= GMBUS_PORT_DPC && port <= GMBUS_PORT_DPD;
+	else
+		return port >= GMBUS_PORT_SSC && port <= GMBUS_PORT_DPD;
 }
 
 extern struct i2c_adapter *intel_gmbus_get_adapter(
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index c684085..e423cc8 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -431,6 +431,7 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
 			  struct bdb_header *bdb)
 {
 	struct bdb_general_definitions *general;
+	struct drm_device *dev = dev_priv->dev;
 
 	general = find_section(bdb, BDB_GENERAL_DEFINITIONS);
 	if (general) {
@@ -438,7 +439,7 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
 		if (block_size >= sizeof(*general)) {
 			int bus_pin = general->crt_ddc_gmbus_pin;
 			DRM_DEBUG_KMS("crt_ddc_bus_pin: %d\n", bus_pin);
-			if (intel_gmbus_is_port_valid(bus_pin))
+			if (intel_gmbus_is_port_valid(dev, bus_pin))
 				dev_priv->vbt.crt_ddc_pin = bus_pin;
 		} else {
 			DRM_DEBUG_KMS("BDB_GD too small (%d). Invalid.\n",
diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
index d857951..27d5b9a 100644
--- a/drivers/gpu/drm/i915/intel_dvo.c
+++ b/drivers/gpu/drm/i915/intel_dvo.c
@@ -499,7 +499,7 @@ void intel_dvo_init(struct drm_device *dev)
 		 * special cases, but otherwise default to what's defined
 		 * in the spec.
 		 */
-		if (intel_gmbus_is_port_valid(dvo->gpio))
+		if (intel_gmbus_is_port_valid(dev, dvo->gpio))
 			gpio = dvo->gpio;
 		else if (dvo->type == INTEL_DVO_CHIP_LVDS)
 			gpio = GMBUS_PORT_SSC;
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 3aa31e1..06892b5 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -619,10 +619,13 @@ err:
 struct i2c_adapter *intel_gmbus_get_adapter(struct drm_i915_private *dev_priv,
 					    unsigned port)
 {
-	WARN_ON(!intel_gmbus_is_port_valid(port));
+	struct drm_device *dev = dev_priv->dev;
+
+	if (WARN_ON(!intel_gmbus_is_port_valid(dev, port)))
+		return NULL;
+
 	/* -1 to map pin pair to gmbus index */
-	return (intel_gmbus_is_port_valid(port)) ?
-		&dev_priv->gmbus[port - 1].adapter : NULL;
+	return &dev_priv->gmbus[port - 1].adapter;
 }
 
 void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 24e8730..094b88e 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -780,7 +780,7 @@ static bool lvds_is_present_in_vbt(struct drm_device *dev,
 		    child->device_type != DEVICE_TYPE_LFP)
 			continue;
 
-		if (intel_gmbus_is_port_valid(child->i2c_pin))
+		if (intel_gmbus_is_port_valid(dev, child->i2c_pin))
 			*i2c_pin = child->i2c_pin;
 
 		/* However, we cannot trust the BIOS writers to populate
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 9e554c2..d68936e 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2283,6 +2283,7 @@ intel_sdvo_select_i2c_bus(struct drm_i915_private *dev_priv,
 			  struct intel_sdvo *sdvo, u32 reg)
 {
 	struct sdvo_device_mapping *mapping;
+	struct drm_device *dev = dev_priv->dev;
 	u8 pin;
 
 	if (sdvo->is_sdvob)
@@ -2290,7 +2291,8 @@ intel_sdvo_select_i2c_bus(struct drm_i915_private *dev_priv,
 	else
 		mapping = &dev_priv->sdvo_mappings[1];
 
-	if (mapping->initialized && intel_gmbus_is_port_valid(mapping->i2c_pin))
+	if (mapping->initialized &&
+		intel_gmbus_is_port_valid(dev, mapping->i2c_pin))
 		pin = mapping->i2c_pin;
 	else
 		pin = GMBUS_PORT_DPB;
-- 
2.1.0