[PATCH v5 8/9] drm/i915/tgl: switch between dc3co and dc5 based on display idleness

Anshuman Gupta
2019-08-09T18:36:21Z

DC3CO is useful power state, when DMC detects PSR2 idle frame
while an active video playback, playing 30fps video on 60hz panel
is the classic example of this use case.
DC5 and DC6 saves more power, but can't be entered during video
playback because there are not enough idle frames in a row to meet
most PSR2 panel deep sleep entry requirement typically 4 frames.

It will be worthy to enable DC3CO after completion of each flip
and switch back to DC5 when display is idle, as driver doesn't
differentiate between video playback and a normal flip.
It is safer to allow DC5 after 6 idle frame, as PSR2 requires
minimum 6 idle frame.

v2: calculated s/w state to switch over dc3co when there is an
update. [Imre]
used cancel_delayed_work_sync() in order to avoid any race
with already scheduled delayed work. [Imre]
v3: cancel_delayed_work_sync() may blocked the commit work.
Hence dropping it, dc5_idle_thread() checks the valid wakeref before
putting the reference count, which avoids any chances of dropping
a zero wakeref. [Imre (IRC)]

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
---
drivers/gpu/drm/i915/display/intel_display.c | 4 +
.../drm/i915/display/intel_display_power.c | 77 +++++++++++++++++++
.../drm/i915/display/intel_display_power.h | 5 ++
drivers/gpu/drm/i915/i915_drv.h | 1 +
4 files changed, 87 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 1ec204c14a10..906a8e6ec9e1 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14082,6 +14082,8 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
intel_uncore_arm_unclaimed_mmio_detection(&dev_priv->uncore);
intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET, wakeref);
}
+
+ tgl_switch_to_dc3co_after_flip(dev_priv);
intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref);

/*
@@ -16157,6 +16159,7 @@ int intel_modeset_init(struct drm_device *dev)
init_llist_head(&dev_priv->atomic_helper.free_list);
INIT_WORK(&dev_priv->atomic_helper.free_work,
intel_atomic_helper_free_state_worker);
+ INIT_DELAYED_WORK(&dev_priv->csr.idle_work, intel_dc5_idle_thread);

intel_init_quirks(dev_priv);

@@ -17100,6 +17103,7 @@ void intel_modeset_driver_remove(struct drm_device *dev)
flush_workqueue(dev_priv->modeset_wq);

flush_work(&dev_priv->atomic_helper.free_work);
+ flush_delayed_work(&dev_priv->csr.idle_work);
WARN_ON(!llist_empty(&dev_priv->atomic_helper.free_list));

/*
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 2667d205fa36..31d0f389ac17 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -19,6 +19,7 @@
#include "intel_sideband.h"
#include "intel_tc.h"
#include "intel_pm.h"
+#include "intel_psr.h"

bool intel_display_power_well_is_enabled(struct drm_i915_private *dev_priv,
enum i915_power_well_id power_well_id);
@@ -825,6 +826,46 @@ void tgl_enable_psr2_transcoder_exitline(struct intel_crtc_state *cstate)
I915_WRITE(EXITLINE(cstate->cpu_transcoder), val);
}

+void tgl_switch_to_dc3co_after_flip(struct drm_i915_private *dev_priv)
+{
+ struct intel_crtc *crtc;
+ struct intel_crtc_state *cstate;
+ u32 delay;
+
+ if (!dev_priv->csr.prefer_dc3co)
+ return;
+
+ mutex_lock(&dev_priv->psr.lock);
+ if (!dev_priv->psr.psr2_enabled || !dev_priv->psr.active)
+ goto unlock;
+
+ /*
+ * As every flip go through intel_atomic_commit, so tracking a
+ * atomic commit will be a hint for idle frames.
+ * Delayed work for 6 idle frames will be enough to allow dc6
+ * over dc3co for deepest power savings.
+ * At every atomic commit first cancel the delayed work ,
+ * when delayed schedules that means display has been idle
+ * for the 6 idle frame.
+ */
+ cancel_delayed_work(&dev_priv->csr.idle_work);
+ mutex_lock(&dev_priv->csr.dc5_mutex);
+ if (!dev_priv->csr.dc5_wakeref) {
+ dev_priv->csr.dc5_wakeref =
+ intel_display_power_get(dev_priv, POWER_DOMAIN_VIDEO);
+ tgl_psr2_deep_sleep_disable(dev_priv);
+ }
+ mutex_unlock(&dev_priv->csr.dc5_mutex);
+ crtc = intel_get_crtc_for_pipe(dev_priv, PIPE_A);
+ cstate = to_intel_crtc_state(crtc->base.state);
+
+ delay = DC5_REQ_IDLE_FRAMES * intel_get_frame_time_us(cstate);
+ schedule_delayed_work(&dev_priv->csr.idle_work,
+ usecs_to_jiffies(delay));
+unlock:
+ mutex_unlock(&dev_priv->psr.lock);
+}
+
static bool tgl_is_only_edp_connected(struct intel_crtc_state *crtc_state)
{
struct drm_atomic_state *state = crtc_state->base.state;
@@ -898,6 +939,20 @@ void tgl_prefer_dc3co_over_dc5_check(struct drm_i915_private *dev_priv,
}
}

+void intel_dc5_idle_thread(struct work_struct *work)
+{
+ intel_wakeref_t wakeref __maybe_unused;
+ struct drm_i915_private *dev_priv =
+ container_of(work, typeof(*dev_priv), csr.idle_work.work);
+
+ mutex_lock(&dev_priv->csr.dc5_mutex);
+ wakeref = fetch_and_zero(&dev_priv->csr.dc5_wakeref);
+ if (wakeref)
+ intel_display_power_put(dev_priv, POWER_DOMAIN_VIDEO, wakeref);
+ tgl_psr2_deep_sleep_enable(dev_priv);
+ mutex_unlock(&dev_priv->csr.dc5_mutex);
+}
+
static void tgl_allow_dc3co(struct drm_i915_private *dev_priv)
{
gen9_set_dc_state(dev_priv, DC_STATE_EN_DC3CO);
@@ -1168,6 +1223,27 @@ static bool tgl_dc3co_power_well_enabled(struct drm_i915_private *dev_priv,
(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5_DC6_MASK) == 0);
}

+u32 intel_get_frame_time_us(const struct intel_crtc_state *cstate)
+{
+ u32 pixel_rate, crtc_htotal, crtc_vtotal;
+ u32 frametime_us;
+
+ if (!cstate || !cstate->base.active)
+ return 0;
+
+ pixel_rate = cstate->pixel_rate;
+
+ if (WARN_ON(pixel_rate == 0))
+ return 0;
+
+ crtc_htotal = cstate->base.adjusted_mode.crtc_htotal;
+ crtc_vtotal = cstate->base.adjusted_mode.crtc_vtotal;
+ frametime_us = DIV_ROUND_UP(crtc_htotal * crtc_vtotal * 1000ULL,
+ pixel_rate);
+
+ return frametime_us;
+}
+
static void i9xx_power_well_sync_hw_noop(struct drm_i915_private *dev_priv,
struct i915_power_well *power_well)
{
@@ -4242,6 +4318,7 @@ int intel_power_domains_init(struct drm_i915_private *dev_priv)
BUILD_BUG_ON(POWER_DOMAIN_NUM > 64);

mutex_init(&power_domains->lock);
+ mutex_init(&dev_priv->csr.dc5_mutex);

INIT_DELAYED_WORK(&power_domains->async_put_work,
intel_display_power_put_async_work);
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 7f4dc8bd2ee4..91e3946e35fe 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -10,6 +10,8 @@
#include "intel_runtime_pm.h"
#include "i915_reg.h"

+#define DC5_REQ_IDLE_FRAMES 6
+
struct drm_i915_private;
struct intel_encoder;
struct intel_crtc_state;
@@ -249,9 +251,12 @@ void intel_display_power_suspend_late(struct drm_i915_private *i915);
void intel_display_power_resume_early(struct drm_i915_private *i915);
void intel_display_power_suspend(struct drm_i915_private *i915);
void intel_display_power_resume(struct drm_i915_private *i915);
+void intel_dc5_idle_thread(struct work_struct *work);
+u32 intel_get_frame_time_us(const struct intel_crtc_state *cstate);
void tgl_prefer_dc3co_over_dc5_check(struct drm_i915_private *dev_priv,
struct intel_atomic_state *state);
void tgl_enable_psr2_transcoder_exitline(struct intel_crtc_state *cstate);
+void tgl_switch_to_dc3co_after_flip(struct drm_i915_private *dev_priv);

const char *
intel_display_power_domain_str(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0a025c692118..6c86138c15b0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -331,6 +331,7 @@ struct intel_csr {
u32 mmiodata[20];
u32 dc_state;
u32 allowed_dc_mask;
+ struct delayed_work idle_work;
intel_wakeref_t wakeref;
bool prefer_dc3co;
intel_wakeref_t dc5_wakeref;
--
2.21.0