drm: Add helpers to kick off self refresh mode in drivers

This patch adds a new drm helper library to help drivers implement
self refresh. Drivers choosing to use it will register crtcs and
will receive callbacks when it's time to enter or exit self refresh
mode.

In its current form, it has a timer which will trigger after a
driver-specified amount of inactivity. When the timer triggers, the
helpers will submit a new atomic commit to shut the refreshing pipe
off. On the next atomic commit, the drm core will revert the self
refresh state and bring everything back up to be actively driven.

From the driver's perspective, this works like a regular disable/enable
cycle. The driver need only check the 'self_refresh_active' state in
crtc_state. It should initiate self refresh mode on the panel and enter
an off or low-power state.

Changes in v2:
- s/psr/self_refresh/ (Daniel)
- integrated the psr exit into the commit that wakes it up (Jose/Daniel)
- made the psr state per-crtc (Jose/Daniel)
Changes in v3:
- Remove the self_refresh_(active|changed) from connector state (Daniel)
- Simplify loop in drm_self_refresh_helper_alter_state (Daniel)
- Improve self_refresh_aware comment (Daniel)
- s/self_refresh_state/self_refresh_data/ (Daniel)
Changes in v4:
- Move docbook location below panel (Daniel)
- Improve docbook with references and more detailed explanation (Daniel)
- Instead of register/unregister, use init/cleanup (Daniel)
Changes in v5:
- Resolved conflict in drm_atomic_helper.c #include block
- Resolved conflict in rst with HDCP helper docs
Changes in v6:
- Fix include ordering, clean up forward declarations (Sam)

Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190228210939.83386-2-sean@poorly.run
Link to v2: https://patchwork.freedesktop.org/patch/msgid/20190326204509.96515-1-sean@poorly.run
Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-6-sean@poorly.run
Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-6-sean@poorly.run
Link to v5: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-6-sean@poorly.run

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jose Souza <jose.souza@intel.com>
Cc: Zain Wang <wzz@rock-chips.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190612145026.191846-1-sean@poorly.run

1 files changed, 33 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index e58be6996069..d9ea7e51ffdc 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -34,6 +34,7 @@
 #include <drm/drm_device.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_print.h>
+#include <drm/drm_self_refresh_helper.h>
 #include <drm/drm_vblank.h>
 #include <drm/drm_writeback.h>
 
@@ -953,10 +954,33 @@ int drm_atomic_helper_check(struct drm_device *dev,
 	if (state->legacy_cursor_update)
 		state->async_update = !drm_atomic_helper_async_check(dev, state);
 
+	drm_self_refresh_helper_alter_state(state);
+
 	return ret;
 }
 EXPORT_SYMBOL(drm_atomic_helper_check);
 
+static bool
+crtc_needs_disable(struct drm_crtc_state *old_state,
+		   struct drm_crtc_state *new_state)
+{
+	/*
+	 * No new_state means the crtc is off, so the only criteria is whether
+	 * it's currently active or in self refresh mode.
+	 */
+	if (!new_state)
+		return drm_atomic_crtc_effectively_active(old_state);
+
+	/*
+	 * We need to run through the crtc_funcs->disable() function if the crtc
+	 * is currently on, if it's transitioning to self refresh mode, or if
+	 * it's in self refresh mode and needs to be fully disabled.
+	 */
+	return old_state->active ||
+	       (old_state->self_refresh_active && !new_state->enable) ||
+	       new_state->self_refresh_active;
+}
+
 static void
 disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 {
@@ -977,7 +1001,14 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 
 		old_crtc_state = drm_atomic_get_old_crtc_state(old_state, old_conn_state->crtc);
 
-		if (!old_crtc_state->active ||
+		if (new_conn_state->crtc)
+			new_crtc_state = drm_atomic_get_new_crtc_state(
+						old_state,
+						new_conn_state->crtc);
+		else
+			new_crtc_state = NULL;
+
+		if (!crtc_needs_disable(old_crtc_state, new_crtc_state) ||
 		    !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
 			continue;
 
@@ -1023,7 +1054,7 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 		if (!drm_atomic_crtc_needs_modeset(new_crtc_state))
 			continue;
 
-		if (!old_crtc_state->active)
+		if (!crtc_needs_disable(old_crtc_state, new_crtc_state))
 			continue;
 
 		funcs = crtc->helper_private;