drm/i915: Improve CRTDDC mapping by using VBT info

Use VBT information to determine which DDC bus to use for CRTDCC.
Fall back to GPIOA if VBT info is not available.

Signed-off-by: David Müller <d.mueller@elsoft.ch>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested on: 855 (David), and 945GM, 965GM, GM45, and G45 (anholt)

3 files changed, 55 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 11fc4b66c889..5b4f87e55621 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -222,6 +222,7 @@ typedef struct drm_i915_private {
         unsigned int edp_support:1;
         int lvds_ssc_freq;
 
+        int crt_ddc_bus; /* -1 = unknown, else GPIO to use for CRT DDC */
         struct drm_i915_fence_reg fence_regs[16]; /* assume 965 */
         int fence_reg_start; /* 4 if userland hasn't ioctl'd us yet */
         int num_fence_regs; /* 8 on pre-965, 16 otherwise */
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 300aee3296c2..f806fcc54e09 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -59,6 +59,16 @@ find_section(struct bdb_header *bdb, int section_id)
         return NULL;
 }
 
+static u16
+get_blocksize(void *p)
+{
+        u16 *block_ptr, block_size;
+
+        block_ptr = (u16 *)((char *)p - 2);
+        block_size = *block_ptr;
+        return block_size;
+}
+
 static void
 fill_detail_timing_data(struct drm_display_mode *panel_fixed_mode,
                         struct lvds_dvo_timing *dvo_timing)
@@ -215,6 +225,41 @@ parse_general_features(struct drm_i915_private *dev_priv,
 }
 
 static void
+parse_general_definitions(struct drm_i915_private *dev_priv,
+                          struct bdb_header *bdb)
+{
+        struct bdb_general_definitions *general;
+        const int crt_bus_map_table[] = {
+                GPIOB,
+                GPIOA,
+                GPIOC,
+                GPIOD,
+                GPIOE,
+                GPIOF,
+        };
+
+        /* Set sensible defaults in case we can't find the general block
+           or it is the wrong chipset */
+        dev_priv->crt_ddc_bus = -1;
+
+        general = find_section(bdb, BDB_GENERAL_DEFINITIONS);
+        if (general) {
+                u16 block_size = get_blocksize(general);
+                if (block_size >= sizeof(*general)) {
+                        int bus_pin = general->crt_ddc_gmbus_pin;
+                        DRM_DEBUG("crt_ddc_bus_pin: %d\n", bus_pin);
+                        if ((bus_pin >= 1) && (bus_pin <= 6)) {
+                                dev_priv->crt_ddc_bus =
+                                        crt_bus_map_table[bus_pin-1];
+                        }
+                } else {
+                        DRM_DEBUG("BDB_GD too small (%d). Invalid.\n",
+                                  block_size);
+                }
+        }
+}
+
+static void
 parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
                        struct bdb_header *bdb)
 {
@@ -222,7 +267,7 @@ parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
         struct bdb_general_definitions *p_defs;
         struct child_device_config *p_child;
         int i, child_device_num, count;
-        u16     block_size, *block_ptr;
+        u16     block_size;
 
         p_defs = find_section(bdb, BDB_GENERAL_DEFINITIONS);
         if (!p_defs) {
@@ -240,8 +285,7 @@ parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
                 return;
         }
         /* get the block size of general definitions */
-        block_ptr = (u16 *)((char *)p_defs - 2);
-        block_size = *block_ptr;
+        block_size = get_blocksize(p_defs);
         /* get the number of child device */
         child_device_num = (block_size - sizeof(*p_defs)) /
                                 sizeof(*p_child);
@@ -362,6 +406,7 @@ intel_init_bios(struct drm_device *dev)
 
         /* Grab useful general definitions */
         parse_general_features(dev_priv, bdb);
+        parse_general_definitions(dev_priv, bdb);
         parse_lfp_panel_data(dev_priv, bdb);
         parse_sdvo_panel_data(dev_priv, bdb);
         parse_sdvo_device_mapping(dev_priv, bdb);
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index d1294978a38c..590f81c8f594 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -508,6 +508,7 @@ void intel_crt_init(struct drm_device *dev)
 {
         struct drm_connector *connector;
         struct intel_output *intel_output;
+        struct drm_i915_private *dev_priv = dev->dev_private;
         u32 i2c_reg;
 
         intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
@@ -527,8 +528,12 @@ void intel_crt_init(struct drm_device *dev)
         /* Set up the DDC bus. */
         if (IS_IGDNG(dev))
                 i2c_reg = PCH_GPIOA;
-        else
+        else {
                 i2c_reg = GPIOA;
+                /* Use VBT information for CRT DDC if available */
+                if (dev_priv->crt_ddc_bus != -1)
+                        i2c_reg = dev_priv->crt_ddc_bus;
+        }
         intel_output->ddc_bus = intel_i2c_create(dev, i2c_reg, "CRTDDC_A");
         if (!intel_output->ddc_bus) {
                 dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "