drm/i915: make edp panel power sequence setup more robust

3 changes:
- If a given value is unset, use the maximal limits from the eDP spec.
- Write back the new values, since otherwise the panel power sequencing
  hw will not dtrt.
- Revert the early bail-out in case the register values are unset.

The last change reverts

commit bfa3384a9a84aaaa59443bbd776c142e7dba4b0f
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Tue Apr 10 11:58:04 2012 -0700

    drm/i915: check PPS regs for sanity when using eDP

v2:
- Unlock the PP regs as the very first thing. This is a required w/a
  for cpu eDP on port A, and generally a good idea.
- Fixup the panel power control port selection bits.

v3: Paulo Zanoni noticed that I've fumbled the computation of the spec
limit values. Fix them up. We've also noticed that the t8/t9 values in
the vbt/bios-programmed pp are much larger than any limits. My guess
is that this is to conceal any backlight enable/disable delays. So by
using the much shorter limits from the spec, which only concerns the
sink, we risk that we might display before the backlight is fully on,
or disable the output while the backlight still has afterglow. I've
figured I don't care too much, since this will only happen when both
the pp regs are not programmed, and the vbt tables don't contain
anything useful.

v4: Don't set the port selection bits on hsw/LPT, they don't exist any
more.

v5: Fixup spelling issues in comments, as noticed by Jesse Barnes.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -4010,6 +4010,11 @@
 #define  PANEL_LIGHT_ON_DELAY_SHIFT	0
 
 #define PCH_PP_OFF_DELAYS	0xc720c
+#define  PANEL_POWER_PORT_SELECT_MASK	(0x3 << 30)
+#define  PANEL_POWER_PORT_LVDS		(0 << 30)
+#define  PANEL_POWER_PORT_DP_A		(1 << 30)
+#define  PANEL_POWER_PORT_DP_C		(2 << 30)
+#define  PANEL_POWER_PORT_DP_D		(3 << 30)
 #define  PANEL_POWER_DOWN_DELAY_MASK	(0x1fff0000)
 #define  PANEL_POWER_DOWN_DELAY_SHIFT	16
 #define  PANEL_LIGHT_OFF_DELAY_MASK	(0x1fff)

drivers/gpu/drm/i915/intel_dp.c

@@ -2633,20 +2633,18 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 
 	/* Cache some DPCD data in the eDP case */
 	if (is_edp(intel_dp)) {
-		struct edp_power_seq	cur, vbt;
-		u32 pp_on, pp_off, pp_div;
+		struct edp_power_seq	cur, vbt, spec, final;
+		u32 pp_on, pp_off, pp_div, pp;
+
+		/* Workaround: Need to write PP_CONTROL with the unlock key as
+		 * the very first thing. */
+		pp = ironlake_get_pp_control(dev_priv);
+		I915_WRITE(PCH_PP_CONTROL, pp);
 
 		pp_on = I915_READ(PCH_PP_ON_DELAYS);
 		pp_off = I915_READ(PCH_PP_OFF_DELAYS);
 		pp_div = I915_READ(PCH_PP_DIVISOR);
 
-		if (!pp_on || !pp_off || !pp_div) {
-			DRM_INFO("bad panel power sequencing delays, disabling panel\n");
-			intel_dp_encoder_destroy(&intel_dp->base.base);
-			intel_dp_destroy(&intel_connector->base);
-			return;
-		}
-
 		/* Pull timing values out of registers */
 		cur.t1_t3 = (pp_on & PANEL_POWER_UP_DELAY_MASK) >>
 			PANEL_POWER_UP_DELAY_SHIFT;
@@ -2668,16 +2666,62 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 
 		vbt = dev_priv->edp.pps;
 
+		/* Upper limits from eDP 1.3 spec. Note that we use the clunky
+		 * units of our hw here, which are all in 100usec. */
+		spec.t1_t3 = 210 * 10;
+		spec.t8 = 50 * 10; /* no limit for t8, use t7 instead */
+		spec.t9 = 50 * 10; /* no limit for t9, make it symmetric with t8 */
+		spec.t10 = 500 * 10;
+		/* This one is special and actually in units of 100ms, but zero
+		 * based in the hw (so we need to add 100 ms). But the sw vbt
+		 * table multiplies it with 1000 to make it in units of 100usec,
+		 * too. */
+		spec.t11_t12 = (510 + 100) * 10;
+
 		DRM_DEBUG_KMS("vbt t1_t3 %d t8 %d t9 %d t10 %d t11_t12 %d\n",
 			      vbt.t1_t3, vbt.t8, vbt.t9, vbt.t10, vbt.t11_t12);
 
-#define get_delay(field)	((max(cur.field, vbt.field) + 9) / 10)
-
+		/* Use the max of the register settings and vbt. If both are
+		 * unset, fall back to the spec limits. */
+#define assign_final(field)	final.field = (max(cur.field, vbt.field) == 0 ? \
+					       spec.field : \
+					       max(cur.field, vbt.field))
+		assign_final(t1_t3);
+		assign_final(t8);
+		assign_final(t9);
+		assign_final(t10);
+		assign_final(t11_t12);
+#undef assign_final
+
+#define get_delay(field)	(DIV_ROUND_UP(final.field, 10))
 		intel_dp->panel_power_up_delay = get_delay(t1_t3);
 		intel_dp->backlight_on_delay = get_delay(t8);
 		intel_dp->backlight_off_delay = get_delay(t9);
 		intel_dp->panel_power_down_delay = get_delay(t10);
 		intel_dp->panel_power_cycle_delay = get_delay(t11_t12);
+#undef get_delay
+
+		/* And finally store the new values in the power sequencer. */
+		pp_on = (final.t1_t3 << PANEL_POWER_UP_DELAY_SHIFT) |
+			(final.t8 << PANEL_LIGHT_ON_DELAY_SHIFT);
+		pp_off = (final.t9 << PANEL_LIGHT_OFF_DELAY_SHIFT) |
+			 (final.t10 << PANEL_POWER_DOWN_DELAY_SHIFT);
+		pp_div = (pp_div & PP_REFERENCE_DIVIDER_MASK) |
+			 (DIV_ROUND_UP(final.t11_t12, 1000) << PANEL_POWER_CYCLE_DELAY_SHIFT);
+
+		/* Haswell doesn't have any port selection bits for the panel
+		 * power sequence any more. */
+		if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev)) {
+			if (is_cpu_edp(intel_dp))
+				pp_on |= PANEL_POWER_PORT_DP_A;
+			else
+				pp_on |= PANEL_POWER_PORT_DP_D;
+		}
+
+		I915_WRITE(PCH_PP_ON_DELAYS, pp_on);
+		I915_WRITE(PCH_PP_OFF_DELAYS, pp_off);
+		I915_WRITE(PCH_PP_DIVISOR, pp_div);
+
 
 		DRM_DEBUG_KMS("panel power up delay %d, power down delay %d, power cycle delay %d\n",
 			      intel_dp->panel_power_up_delay, intel_dp->panel_power_down_delay,
@@ -2685,6 +2729,11 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 
 		DRM_DEBUG_KMS("backlight on delay %d, off delay %d\n",
 			      intel_dp->backlight_on_delay, intel_dp->backlight_off_delay);
+
+		DRM_DEBUG_KMS("panel power sequencer register settings: PP_ON %#x, PP_OFF %#x, PP_DIV %#x\n",
+			      I915_READ(PCH_PP_ON_DELAYS),
+			      I915_READ(PCH_PP_OFF_DELAYS),
+			      I915_READ(PCH_PP_DIVISOR));
 	}
 
 	intel_dp_i2c_init(intel_dp, intel_connector, name);