linux/drivers/gpu/drm/i915/display/intel_drrs.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2021 Intel Corporation
 */

#include "i915_drv.h"
#include "i915_reg.h"
#include "intel_atomic.h"
#include "intel_de.h"
#include "intel_display_types.h"
#include "intel_drrs.h"
#include "intel_frontbuffer.h"
#include "intel_panel.h"

/**
 * DOC: Display Refresh Rate Switching (DRRS)
 *
 * Display Refresh Rate Switching (DRRS) is a power conservation feature
 * which enables swtching between low and high refresh rates,
 * dynamically, based on the usage scenario. This feature is applicable
 * for internal panels.
 *
 * Indication that the panel supports DRRS is given by the panel EDID, which
 * would list multiple refresh rates for one resolution.
 *
 * DRRS is of 2 types - static and seamless.
 * Static DRRS involves changing refresh rate (RR) by doing a full modeset
 * (may appear as a blink on screen) and is used in dock-undock scenario.
 * Seamless DRRS involves changing RR without any visual effect to the user
 * and can be used during normal system usage. This is done by programming
 * certain registers.
 *
 * Support for static/seamless DRRS may be indicated in the VBT based on
 * inputs from the panel spec.
 *
 * DRRS saves power by switching to low RR based on usage scenarios.
 *
 * The implementation is based on frontbuffer tracking implementation.  When
 * there is a disturbance on the screen triggered by user activity or a periodic
 * system activity, DRRS is disabled (RR is changed to high RR).  When there is
 * no movement on screen, after a timeout of 1 second, a switch to low RR is
 * made.
 *
 * For integration with frontbuffer tracking code, intel_drrs_invalidate()
 * and intel_drrs_flush() are called.
 *
 * DRRS can be further extended to support other internal panels and also
 * the scenario of video playback wherein RR is set based on the rate
 * requested by userspace.
 */

const char *intel_drrs_type_str(enum drrs_type drrs_type)
{ … }

bool intel_cpu_transcoder_has_drrs(struct drm_i915_private *i915,
				   enum transcoder cpu_transcoder)
{ … }

static void
intel_drrs_set_refresh_rate_pipeconf(struct intel_crtc *crtc,
				     enum drrs_refresh_rate refresh_rate)
{ … }

static void
intel_drrs_set_refresh_rate_m_n(struct intel_crtc *crtc,
				enum drrs_refresh_rate refresh_rate)
{ … }

bool intel_drrs_is_active(struct intel_crtc *crtc)
{ … }

static void intel_drrs_set_state(struct intel_crtc *crtc,
				 enum drrs_refresh_rate refresh_rate)
{ … }

static void intel_drrs_schedule_work(struct intel_crtc *crtc)
{ … }

static unsigned int intel_drrs_frontbuffer_bits(const struct intel_crtc_state *crtc_state)
{ … }

/**
 * intel_drrs_activate - activate DRRS
 * @crtc_state: the crtc state
 *
 * Activates DRRS on the crtc.
 */
void intel_drrs_activate(const struct intel_crtc_state *crtc_state)
{ … }

/**
 * intel_drrs_deactivate - deactivate DRRS
 * @old_crtc_state: the old crtc state
 *
 * Deactivates DRRS on the crtc.
 */
void intel_drrs_deactivate(const struct intel_crtc_state *old_crtc_state)
{ … }

static void intel_drrs_downclock_work(struct work_struct *work)
{ … }

static void intel_drrs_frontbuffer_update(struct drm_i915_private *dev_priv,
					  unsigned int all_frontbuffer_bits,
					  bool invalidate)
{ … }

/**
 * intel_drrs_invalidate - Disable Idleness DRRS
 * @dev_priv: i915 device
 * @frontbuffer_bits: frontbuffer plane tracking bits
 *
 * This function gets called everytime rendering on the given planes start.
 * Hence DRRS needs to be Upclocked, i.e. (LOW_RR -> HIGH_RR).
 *
 * Dirty frontbuffers relevant to DRRS are tracked in busy_frontbuffer_bits.
 */
void intel_drrs_invalidate(struct drm_i915_private *dev_priv,
			   unsigned int frontbuffer_bits)
{ … }

/**
 * intel_drrs_flush - Restart Idleness DRRS
 * @dev_priv: i915 device
 * @frontbuffer_bits: frontbuffer plane tracking bits
 *
 * This function gets called every time rendering on the given planes has
 * completed or flip on a crtc is completed. So DRRS should be upclocked
 * (LOW_RR -> HIGH_RR). And also Idleness detection should be started again,
 * if no other planes are dirty.
 *
 * Dirty frontbuffers relevant to DRRS are tracked in busy_frontbuffer_bits.
 */
void intel_drrs_flush(struct drm_i915_private *dev_priv,
		      unsigned int frontbuffer_bits)
{ … }

/**
 * intel_drrs_crtc_init - Init DRRS for CRTC
 * @crtc: crtc
 *
 * This function is called only once at driver load to initialize basic
 * DRRS stuff.
 *
 */
void intel_drrs_crtc_init(struct intel_crtc *crtc)
{ … }

static int intel_drrs_debugfs_status_show(struct seq_file *m, void *unused)
{ … }

DEFINE_SHOW_ATTRIBUTE(…);

static int intel_drrs_debugfs_ctl_set(void *data, u64 val)
{ … }

DEFINE_DEBUGFS_ATTRIBUTE(…);

void intel_drrs_crtc_debugfs_add(struct intel_crtc *crtc)
{ … }

static int intel_drrs_debugfs_type_show(struct seq_file *m, void *unused)
{ … }

DEFINE_SHOW_ATTRIBUTE(…);

void intel_drrs_connector_debugfs_add(struct intel_connector *connector)
{ … }