drm/i915: Check VBIOS value for determining LVDS dual channel mode, too
Currently i915 driver checks [PCH_]LVDS register bits to decide
whether to set up the dual-link or the single-link mode. This relies
implicitly on that BIOS initializes the register properly at boot.
However, BIOS doesn't initialize it always. When the machine is
booted with the closed lid, BIOS skips the LVDS reg initialization.
This ends up in blank output on a machine with a dual-link LVDS when
you open the lid after the boot.
This patch adds a workaround for that problem by checking the initial
LVDS register value in VBT.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=37742
Tested-By: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 683002fb..a76ac2e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -360,6 +360,27 @@
.find_pll = intel_find_pll_ironlake_dp,
};
+static bool is_dual_link_lvds(struct drm_i915_private *dev_priv,
+ unsigned int reg)
+{
+ unsigned int val;
+
+ if (dev_priv->lvds_val)
+ val = dev_priv->lvds_val;
+ else {
+ /* BIOS should set the proper LVDS register value at boot, but
+ * in reality, it doesn't set the value when the lid is closed;
+ * we need to check "the value to be set" in VBT when LVDS
+ * register is uninitialized.
+ */
+ val = I915_READ(reg);
+ if (!(val & ~LVDS_DETECTED))
+ val = dev_priv->bios_lvds_val;
+ dev_priv->lvds_val = val;
+ }
+ return (val & LVDS_CLKB_POWER_MASK) == LVDS_CLKB_POWER_UP;
+}
+
static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,
int refclk)
{
@@ -368,8 +389,7 @@
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 (is_dual_link_lvds(dev_priv, PCH_LVDS)) {
/* LVDS dual channel */
if (refclk == 100000)
limit = &intel_limits_ironlake_dual_lvds_100m;
@@ -397,8 +417,7 @@
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 (is_dual_link_lvds(dev_priv, LVDS))
/* LVDS with dual channel */
limit = &intel_limits_g4x_dual_channel_lvds;
else
@@ -536,8 +555,7 @@
* 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 (is_dual_link_lvds(dev_priv, LVDS))
clock.p2 = limit->p2.p2_fast;
else
clock.p2 = limit->p2.p2_slow;