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authorVille Syrjälä <ville.syrjala@linux.intel.com>2014-10-16 20:46:10 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-12-06 15:57:34 -0800
commit9a3c5ffb94f165d9a076207ac11dc2c531beb3a8 (patch)
treea4d504274aa3fa9184aeaf10fb1a318794dc1ffe
parentfb14996c2a555322ae2610d783e614430b259592 (diff)
downloadlwn-9a3c5ffb94f165d9a076207ac11dc2c531beb3a8.tar.gz
lwn-9a3c5ffb94f165d9a076207ac11dc2c531beb3a8.zip
drm/i915: Ignore long hpds on eDP ports
original upstream id: 7a7f84ccb82e542c845c43f604665ccea1247866 Turning vdd on/off can generate a long hpd pulse on eDP ports. In order to handle hpd we would need to turn on vdd to perform aux transfers. This would lead to an endless cycle of "vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..." So ignore long hpd pulses on eDP ports. eDP panels should be physically tied to the machine anyway so they should not actually disappear and thus don't need long hpd handling. Short hpds are still needed for link re-train and whatnot so we can't just turn off the hpd interrupt entirely for eDP ports. Perhaps we could turn it off whenever the panel is disabled, but just ignoring the long hpd seems sufficient. Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Dave Airlie <airlied@redhat.com> Reviewed-by: Todd Previte <tprevite@gmail.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/gpu/drm/i915/intel_dp.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 4b3c09636990..1b7375efc670 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4084,6 +4084,18 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
if (intel_dig_port->base.type != INTEL_OUTPUT_EDP)
intel_dig_port->base.type = INTEL_OUTPUT_DISPLAYPORT;
+ if (long_hpd && intel_dig_port->base.type == INTEL_OUTPUT_EDP) {
+ /*
+ * vdd off can generate a long pulse on eDP which
+ * would require vdd on to handle it, and thus we
+ * would end up in an endless cycle of
+ * "vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..."
+ */
+ DRM_DEBUG_KMS("ignoring long hpd on eDP port %c\n",
+ port_name(intel_dig_port->port));
+ return false;
+ }
+
DRM_DEBUG_KMS("got hpd irq on port %d - %s\n", intel_dig_port->port,
long_hpd ? "long" : "short");