[PATCH v3] drm/i915: Re-init lspcon after HPD if lspcon probe failed

[Kai-Heng Feng]

On HP 800 G4 DM, if HDMI cable isn't plugged before boot, the HDMI port
becomes useless and never responds to cable hotplugging:
[    3.031904] [drm:lspcon_init [i915]] *ERROR* Failed to probe lspcon
[    3.031945] [drm:intel_ddi_init [i915]] *ERROR* LSPCON init failed on port D

Seems like the lspcon chip on the system in question only gets powered
after the cable is plugged.

So let's call lspcon_init() dynamically to properly initialize the
lspcon chip and make HDMI port work.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/203
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
v3:
 - Make sure it's handled under long HPD case.

v2: 
 - Move lspcon_init() inside of intel_dp_hpd_pulse().

 drivers/gpu/drm/i915/display/intel_dp.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index fe31bbfd6c62..a72c9c041c60 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -6573,6 +6573,7 @@ enum irqreturn
 intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 {
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
 
 	if (long_hpd && intel_dig_port->base.type == INTEL_OUTPUT_EDP) {
 		/*
@@ -6593,7 +6594,12 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 		      long_hpd ? "long" : "short");
 
 	if (long_hpd) {
-		intel_dp->reset_link_params = true;
+		if (intel_dig_port->base.type == INTEL_OUTPUT_DDI &&
+		    HAS_LSPCON(dev_priv) && !intel_dig_port->lspcon.active)
+			lspcon_init(intel_dig_port);
+		else
+			intel_dp->reset_link_params = true;
+
 		return IRQ_NONE;
 	}
 
-- 
2.17.1