0001-i915-manual-override-of-lvds-channel-mode.patch

commit e3cb536f63bd8e7e0220b801e37434fc13a2df2d
Author: Dan Yang <dsyang92 (at) gmail (dot) com>
Date:   Sat Apr 7 17:58:33 2012 -0400

    Implement manual override of LVDS single/dual channel mode (updated)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index d04597d..2bee604 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -74,6 +74,10 @@ MODULE_PARM_DESC(i915_enable_fbc,
        "Enable frame buffer compression for power savings "
        "(default: -1 (use per-chip default))");

+unsigned int i915_lvds_channels __read_mostly = 0;
+module_param_named(lvds_channels, i915_lvds_channels, int, 0600);
+MODULE_PARM_DESC(lvds_channels, "LVDS channels in use: 0=(default) prove hardware 1=single 2=dual");
+
 unsigned int i915_lvds_downclock __read_mostly = 0;
 module_param_named(lvds_downclock, i915_lvds_downclock, int, 0400);
 MODULE_PARM_DESC(lvds_downclock,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ae294a0..6b1a198 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1010,6 +1010,7 @@ extern int i915_panel_ignore_lid __read_mostly;
 extern unsigned int i915_powersave __read_mostly;
 extern int i915_semaphores __read_mostly;
 extern unsigned int i915_lvds_downclock __read_mostly;
+extern unsigned int i915_lvds_channels __read_mostly;
 extern int i915_panel_use_ssc __read_mostly;
 extern int i915_vbt_sdvo_panel_type __read_mostly;
 extern int i915_enable_rc6 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9ec9755..c3dbb35 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -356,6 +356,19 @@ static const intel_limit_t intel_limits_ironlake_display_port = {
    .find_pll = intel_find_pll_ironlake_dp,
 };

+static int intel_is_dual_channel_mode(struct drm_crtc *crtc)
+{
+   struct drm_device *dev = crtc->dev;
+   struct drm_i915_private *dev_priv = dev->dev_private;
+   if(i915_lvds_channels) {
+       /* user specified desired channel mode */
+       return (i915_lvds_channels == 2);
+   }
+
+   /* User did not specify mode so probe hardware */
+   return ((I915_READ(PCH_LVDS) & LVDS_CLKB_POWER_MASK) == LVDS_CLKB_POWER_UP);
+}
+
 static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,
                        int refclk)
 {
@@ -364,8 +377,7 @@ static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,
    const intel_limit_t *limit;

    if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
-       if ((I915_READ(PCH_LVDS) & LVDS_CLKB_POWER_MASK) ==
-           LVDS_CLKB_POWER_UP) {
+       if (intel_is_dual_channel_mode(crtc)) {
            /* LVDS dual channel */
            if (refclk == 100000)
                limit = &intel_limits_ironlake_dual_lvds_100m;
@@ -388,18 +400,16 @@ static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,

 static const intel_limit_t *intel_g4x_limit(struct drm_crtc *crtc)
 {
-   struct drm_device *dev = crtc->dev;
-   struct drm_i915_private *dev_priv = dev->dev_private;
    const intel_limit_t *limit;

    if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
-       if ((I915_READ(LVDS) & LVDS_CLKB_POWER_MASK) ==
-           LVDS_CLKB_POWER_UP)
+       if (intel_is_dual_channel_mode(crtc)) {
            /* LVDS with dual channel */
            limit = &intel_limits_g4x_dual_channel_lvds;
-       else
-           /* LVDS with dual channel */
+       } else {
+           /* LVDS with single channel */
            limit = &intel_limits_g4x_single_channel_lvds;
+       }
    } else if (intel_pipe_has_type(crtc, INTEL_OUTPUT_HDMI) ||
           intel_pipe_has_type(crtc, INTEL_OUTPUT_ANALOG)) {
        limit = &intel_limits_g4x_hdmi;
@@ -531,8 +541,7 @@ intel_find_best_PLL(const intel_limit_t *limit, struct drm_crtc *crtc,
         * reliably set up different single/dual channel state, if we
         * even can.
         */
-       if ((I915_READ(LVDS) & LVDS_CLKB_POWER_MASK) ==
-           LVDS_CLKB_POWER_UP)
+       if (intel_is_dual_channel_mode(crtc))
            clock.p2 = limit->p2.p2_fast;
        else
            clock.p2 = limit->p2.p2_slow;
@@ -581,7 +590,6 @@ intel_g4x_find_best_PLL(const intel_limit_t *limit, struct drm_crtc *crtc,
            int target, int refclk, intel_clock_t *best_clock)
 {
    struct drm_device *dev = crtc->dev;
-   struct drm_i915_private *dev_priv = dev->dev_private;
    intel_clock_t clock;
    int max_n;
    bool found;
@@ -596,8 +604,7 @@ intel_g4x_find_best_PLL(const intel_limit_t *limit, struct drm_crtc *crtc,
            lvds_reg = PCH_LVDS;
        else
            lvds_reg = LVDS;
-       if ((I915_READ(lvds_reg) & LVDS_CLKB_POWER_MASK) ==
-           LVDS_CLKB_POWER_UP)
+       if (intel_is_dual_channel_mode(crtc))
            clock.p2 = limit->p2.p2_fast;
        else
            clock.p2 = limit->p2.p2_slow;