[PATCH v2] i915: Add option to bypass vbt table.

[Mathias.Froehlich at gmx.net]

From: Mathias Fröhlich <Mathias.Froehlich at web.de>

Add an option to skip reading the mode entries from
the vbt bios tables.
This change enables the use of displays where the vbt table just
contains inappropriate values, but either the vesa defaults or
the video=... modes do something sensible with the attached display.

Reviewed-by: Paul Menzel <paulepanter at users.sourceforge.net>
Signed-off-by: Mathias Froehlich <Mathias.Froehlich at web.de>
---
 drivers/gpu/drm/i915/i915_drv.c   |    4 ++--
 drivers/gpu/drm/i915/intel_bios.c |    5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 308f819..0975895 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -89,8 +89,8 @@ MODULE_PARM_DESC(lvds_use_ssc,
 int i915_vbt_sdvo_panel_type __read_mostly = -1;
 module_param_named(vbt_sdvo_panel_type, i915_vbt_sdvo_panel_type, int, 0600);
 MODULE_PARM_DESC(vbt_sdvo_panel_type,
-		"Override selection of SDVO panel mode in the VBT "
-		"(default: auto)");
+		"Override/Ignore selection of SDVO panel mode in the VBT "
+		"(-2=ignore, -1=auto [default], index in VBT BIOS table)");
 
 static bool i915_try_reset __read_mostly = true;
 module_param_named(reset, i915_try_reset, bool, 0600);
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 63880e2..7670b09 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -255,6 +255,11 @@ parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 	int index;
 
 	index = i915_vbt_sdvo_panel_type;
+	if (index == -2) {
+		DRM_DEBUG_KMS("Ignore SDVO panel mode from BIOS VBT tables.\n");
+		return;
+	}
+
 	if (index == -1) {
 		struct bdb_sdvo_lvds_options *sdvo_lvds_options;
 
-- 
1.7.1