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drm/i915: Filter out glitches on HPD lines during hotplug detection
Glitches deasserting the connector HPD line can lead to incorrectly detecting a disconnect event (a glitch asserting the line will only cause a redundant connect->disconnect transition). The source of such a glitch can be noise on the line or a 0.5ms-1ms MST IRQ_HPD pulse. TypeC ports in the DP-alt or TBT-alt mode filter out these glitches inernally, but for others the driver has to do this. Make it so by polling the HPD line on these connectors for 4 ms. Link: https://patchwork.freedesktop.org/patch/msgid/20240104083008.2715733-12-imre.deak@intel.com Reviewed-by: Jouni Högander <jouni.hogander@intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com>
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3 changed files with 21 additions and 2 deletions
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@ -5460,11 +5460,20 @@ bool intel_digital_port_connected_locked(struct intel_encoder *encoder)
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{
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struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
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struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
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bool is_glitch_free = intel_tc_port_handles_hpd_glitches(dig_port);
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bool is_connected = false;
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intel_wakeref_t wakeref;
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with_intel_display_power(dev_priv, POWER_DOMAIN_DISPLAY_CORE, wakeref)
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is_connected = dig_port->connected(encoder);
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with_intel_display_power(dev_priv, POWER_DOMAIN_DISPLAY_CORE, wakeref) {
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unsigned long wait_expires = jiffies + msecs_to_jiffies_timeout(4);
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do {
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is_connected = dig_port->connected(encoder);
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if (is_connected || is_glitch_free)
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break;
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usleep_range(10, 30);
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} while (time_before(jiffies, wait_expires));
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}
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return is_connected;
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}
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@ -122,6 +122,15 @@ bool intel_tc_port_in_legacy_mode(struct intel_digital_port *dig_port)
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return intel_tc_port_in_mode(dig_port, TC_PORT_LEGACY);
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}
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bool intel_tc_port_handles_hpd_glitches(struct intel_digital_port *dig_port)
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{
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struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
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enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
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struct intel_tc_port *tc = to_tc_port(dig_port);
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return intel_phy_is_tc(i915, phy) && !tc->legacy_port;
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}
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/*
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* The display power domains used for TC ports depending on the
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* platform and TC mode (legacy, DP-alt, TBT):
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@ -15,6 +15,7 @@ struct intel_encoder;
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bool intel_tc_port_in_tbt_alt_mode(struct intel_digital_port *dig_port);
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bool intel_tc_port_in_dp_alt_mode(struct intel_digital_port *dig_port);
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bool intel_tc_port_in_legacy_mode(struct intel_digital_port *dig_port);
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bool intel_tc_port_handles_hpd_glitches(struct intel_digital_port *dig_port);
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bool intel_tc_port_connected(struct intel_encoder *encoder);
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