[PATCH v2] 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.

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
v2: 
  - Move lspcon_init() inside of intel_dp_hpd_pulse().

 drivers/gpu/drm/i915/display/intel_dp.c | 6 +++++-
 1 file changed, 5 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..eb395b45527e 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) {
 		/*
@@ -6592,11 +6593,14 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 		      intel_dig_port->base.base.name,
 		      long_hpd ? "long" : "short");
 
-	if (long_hpd) {
+	if (long_hpd && intel_dig_port->base.type != INTEL_OUTPUT_DDI) {
 		intel_dp->reset_link_params = true;
 		return IRQ_NONE;
 	}
 
+	if (long_hpd && HAS_LSPCON(dev_priv) && !intel_dig_port->lspcon.active)
+		lspcon_init(intel_dig_port);
+
 	if (intel_dp->is_mst) {
 		if (intel_dp_check_mst_status(intel_dp) == -EINVAL) {
 			/*
-- 
2.17.1