linux/drivers/gpu/drm/i915/display/intel_hotplug.h

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/* SPDX-License-Identifier: MIT */
/*
* Copyright © 2019 Intel Corporation
*/
#ifndef __INTEL_HOTPLUG_H__
#define __INTEL_HOTPLUG_H__
#include <linux/types.h>
struct drm_i915_private;
struct intel_connector;
drm/i915/dp_mst: Work around out-of-spec adapters filtering short pulses Some TypeC -> native DP adapters, at least the Club 3D CAC-1557 adapter, incorrectly filter out HPD short pulses with a duration less than ~540 usec, leading to MST probe failures. According to the DP Standard 2.0 section 5.1.4: - DP sinks should generate short pulses in the 500 usec -> 1 msec range - DP sources should detect short pulses in the 250 usec -> 2 msec range According to the DP Alt Mode on TypeC Standard section 3.9.2, adapters should detect and forward short pulses according to how sources should detect them as specified in the DP Standard (250 usec -> 2 msec). Based on the above filtering out short pulses with a duration less than 540 usec is incorrect. To make such adapters work add support for a driver polling on MST inerrupt flags, and wire this up in the i915 driver. The sink can clear an interrupt it raised after 110 msec if the source doesn't respond, so use a 50 msec poll period to avoid missing an interrupt. Polling of the MST interrupt flags is explicitly allowed by the DP Standard. This fixes MST probe failures I saw using this adapter and a DELL U2515H monitor. v2: - Fix the wait event timeout for the no-poll case. v3 (Ville): - Fix the short pulse duration limits in the commit log prescribed by the DP Standard. - Add code comment explaining why/how polling is used. - Factor out a helper to schedule the port's hpd irq handler and move it to the rest of hotplug handlers. - Document the new MST callback. - s/update_hpd_irq_state/poll_hpd_irq/ Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200604184500.23730-2-imre.deak@intel.com
2020-06-04 18:45:00 +00:00
struct intel_digital_port;
struct intel_encoder;
enum port;
drm/i915: Reorder hpd init vs. display resume Currently we call .hpd_irq_setup() directly just before display resume, and follow it with another call via intel_hpd_init() just afterwards. Assuming the hpd pins are marked as enabled during the open-coded call these two things do exactly the same thing (ie. enable HPD interrupts). Which even makes sense since we definitely need working HPD interrupts for MST sideband during the display resume. So let's nuke the open-coded call and move the intel_hpd_init() call earlier. However we need to leave the poll_init_work stuff behind after the display resume as that will trigger display detection while we're resuming. We don't want that trampling over the display resume process. To make this a bit more symmetric we turn this into a intel_hpd_poll_{enable,disable}() pair. So we end up with the following transformation: intel_hpd_poll_init() -> intel_hpd_poll_enable() lone intel_hpd_init() -> intel_hpd_init()+intel_hpd_poll_disable() .hpd_irq_setup()+resume+intel_hpd_init() -> intel_hpd_init()+resume+intel_hpd_poll_disable() If we really would like to prevent all *long* HPD processing during display resume we'd need some kind of software mechanism to simply ignore all long HPDs. Currently we appear to have that just for fbdev via ifbdev->hpd_suspended. Since we aren't exploding left and right all the time I guess that's mostly sufficient. For a bit of history on this, we first got a mechanism to block hotplug processing during suspend in commit 15239099d7a7 ("drm/i915: enable irqs earlier when resuming") on account of moving the irq enable earlier. This then got removed in commit 50c3dc970a09 ("drm/fb-helper: Fix hpd vs. initial config races") because the fdev initial config got pushed to a later point. The second ad-hoc hpd_irq_setup() for resume was added in commit 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)") to be able to do MST sideband during the resume. And finally we got a partial resurrection of the hpd blocking mechanism in commit e8a8fedd57fd ("drm/i915: Block fbdev HPD processing during suspend"), but this time it only prevent fbdev from handling hpd while resuming. v2: Leave the poll_init_work behind v3: Remove the extra intel_hpd_poll_disable() from display reset (Lyude) Add the missing intel_hpd_poll_disable() to display init (Imre) Cc: Lyude Paul <lyude@redhat.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20201013181137.30560-1-ville.syrjala@linux.intel.com Reviewed-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Lyude Paul <lyude@redhat.com>
2020-10-13 18:11:37 +00:00
void intel_hpd_poll_enable(struct drm_i915_private *dev_priv);
void intel_hpd_poll_disable(struct drm_i915_private *dev_priv);
enum intel_hotplug_state intel_encoder_hotplug(struct intel_encoder *encoder,
struct intel_connector *connector);
void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
u32 pin_mask, u32 long_mask);
drm/i915/dp_mst: Work around out-of-spec adapters filtering short pulses Some TypeC -> native DP adapters, at least the Club 3D CAC-1557 adapter, incorrectly filter out HPD short pulses with a duration less than ~540 usec, leading to MST probe failures. According to the DP Standard 2.0 section 5.1.4: - DP sinks should generate short pulses in the 500 usec -> 1 msec range - DP sources should detect short pulses in the 250 usec -> 2 msec range According to the DP Alt Mode on TypeC Standard section 3.9.2, adapters should detect and forward short pulses according to how sources should detect them as specified in the DP Standard (250 usec -> 2 msec). Based on the above filtering out short pulses with a duration less than 540 usec is incorrect. To make such adapters work add support for a driver polling on MST inerrupt flags, and wire this up in the i915 driver. The sink can clear an interrupt it raised after 110 msec if the source doesn't respond, so use a 50 msec poll period to avoid missing an interrupt. Polling of the MST interrupt flags is explicitly allowed by the DP Standard. This fixes MST probe failures I saw using this adapter and a DELL U2515H monitor. v2: - Fix the wait event timeout for the no-poll case. v3 (Ville): - Fix the short pulse duration limits in the commit log prescribed by the DP Standard. - Add code comment explaining why/how polling is used. - Factor out a helper to schedule the port's hpd irq handler and move it to the rest of hotplug handlers. - Document the new MST callback. - s/update_hpd_irq_state/poll_hpd_irq/ Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200604184500.23730-2-imre.deak@intel.com
2020-06-04 18:45:00 +00:00
void intel_hpd_trigger_irq(struct intel_digital_port *dig_port);
void intel_hpd_init(struct drm_i915_private *dev_priv);
void intel_hpd_init_work(struct drm_i915_private *dev_priv);
void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
enum port port);
bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
#endif /* __INTEL_HOTPLUG_H__ */