drm/i915: replace ad-hoc dual-link lvds checks

... with is_dual_link_lvds introduced in

commit b03543857fd75876b96e10d4320b775e95041bb7
Author: Takashi Iwai <tiwai@suse.de>
Date:   Tue Mar 20 13:07:05 2012 +0100

    drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

All these checks predate this commit and have simply been overlooked.
Since we don't support switching between single-link and dual-link
modes anyway, this different checks could at best only get in the way
of refactorings, and in the worst case cause inconsistencies.

v2: Update the comment, we now have a solid way to figure out whether
we need dual-link lvds or not (falling back to vbt values as a last
resort). We still don't know how to switch between dual-link and
single link so leave that part intact. I'm not sure though whether
switching between these two modes makes any sense - we always drive
the panel at its fixed mode (with a fixed bpc) anyway ...

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 6 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 55d3e3dbc137..be19b6d1ca52 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -690,13 +690,11 @@ intel_find_best_PLL(const intel_limit_t *limit, struct drm_crtc *crtc,
         intel_clock_t clock;
         int err = target;
 
-        if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) &&
-            (I915_READ(LVDS)) != 0) {
+        if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
                 /*
-                 * For LVDS, if the panel is on, just rely on its current
-                 * settings for dual-channel.  We haven't figured out how to
-                 * reliably set up different single/dual channel state, if we
-                 * even can.
+                 * For LVDS just rely on its current settings for dual-channel.
+                 * We haven't figured out how to reliably set up different
+                 * single/dual channel state, if we even can.
                  */
                 if (is_dual_link_lvds(dev_priv, LVDS))
                         clock.p2 = limit->p2.p2_fast;
@@ -766,8 +764,7 @@ 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 (is_dual_link_lvds(dev_priv, lvds_reg))
                         clock.p2 = limit->p2.p2_fast;
                 else
                         clock.p2 = limit->p2.p2_slow;
@@ -5359,7 +5356,7 @@ static uint32_t ironlake_compute_dpll(struct intel_crtc *intel_crtc,
         if (is_lvds) {
                 if ((intel_panel_use_ssc(dev_priv) &&
                      dev_priv->lvds_ssc_freq == 100) ||
-                    (I915_READ(PCH_LVDS) & LVDS_CLKB_POWER_MASK) == LVDS_CLKB_POWER_UP)
+                    is_dual_link_lvds(dev_priv, PCH_LVDS))
                         factor = 25;
         } else if (is_sdvo && is_tv)
                 factor = 20;