drm/rockchip: Don't fully disable vop on self refresh

Instead of fully disabling and re-enabling the vop on self refresh
transitions, only disable the active windows. This will speed up
self refresh exits substantially and is still a power-savings win.

This patch integrates portions of Zain's patch from here:
https://patchwork.kernel.org/patch/9615063/

Changes in v2:
- None
Changes in v3:
- None
Changes in v4:
- Adjust for preceding vop_win_disable changes
Changes in v5:
- None

Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190228210939.83386-5-sean@poorly.run
Link to v2: https://patchwork.freedesktop.org/patch/msgid/20190326204509.96515-4-sean@poorly.run
Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-10-sean@poorly.run
Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-11-sean@poorly.run

Cc: Zain Wang <wzz@rock-chips.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Kristian H. Kristensen <hoegsberg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-11-sean@poorly.run

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -127,6 +127,7 @@ struct vop {
 	bool is_enabled;
 
 	struct completion dsp_hold_completion;
+	unsigned int win_enabled;
 
 	/* protected by dev->event_lock */
 	struct drm_pending_vblank_event *event;
@@ -543,6 +544,7 @@ static void vop_win_disable(struct vop *vop, const struct vop_win *vop_win)
 	}
 
 	VOP_WIN_SET(vop, win, enable, 0);
+	vop->win_enabled &= ~BIT(VOP_WIN_TO_INDEX(vop_win));
 }
 
 static int vop_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
@@ -625,6 +627,25 @@ static int vop_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
 	return ret;
 }
 
+static void rockchip_drm_set_win_enabled(struct drm_crtc *crtc, bool enabled)
+{
+        struct vop *vop = to_vop(crtc);
+        int i;
+
+        spin_lock(&vop->reg_lock);
+
+        for (i = 0; i < vop->data->win_size; i++) {
+                struct vop_win *vop_win = &vop->win[i];
+                const struct vop_win_data *win = vop_win->data;
+
+                VOP_WIN_SET(vop, win, enable,
+                            enabled && (vop->win_enabled & BIT(i)));
+        }
+        vop_cfg_done(vop);
+
+        spin_unlock(&vop->reg_lock);
+}
+
 static void vop_crtc_atomic_disable(struct drm_crtc *crtc,
 				    struct drm_crtc_state *old_state)
 {
@@ -632,15 +653,16 @@ static void vop_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	WARN_ON(vop->event);
 
-	mutex_lock(&vop->vop_lock);
+	if (crtc->state->self_refresh_active)
+		rockchip_drm_set_win_enabled(crtc, false);
 
-	if (!vop->is_enabled) {
-		mutex_unlock(&vop->vop_lock);
-		return;
-	}
+	mutex_lock(&vop->vop_lock);
 
 	drm_crtc_vblank_off(crtc);
 
+	if (crtc->state->self_refresh_active)
+		goto out;
+
 	/*
 	 * Vop standby will take effect at end of current frame,
 	 * if dsp hold valid irq happen, it means standby complete.
@@ -671,6 +693,8 @@ static void vop_crtc_atomic_disable(struct drm_crtc *crtc,
 	clk_disable(vop->dclk);
 	vop_core_clks_disable(vop);
 	pm_runtime_put(vop->dev);
+
+out:
 	mutex_unlock(&vop->vop_lock);
 
 	if (crtc->state->event && !crtc->state->active) {
@@ -888,6 +912,7 @@ static void vop_plane_atomic_update(struct drm_plane *plane,
 	}
 
 	VOP_WIN_SET(vop, win, enable, 1);
+	vop->win_enabled |= BIT(win_index);
 	spin_unlock(&vop->reg_lock);
 }
 
@@ -1046,6 +1071,12 @@ static void vop_crtc_atomic_enable(struct drm_crtc *crtc,
 	int dither_bpc = s->output_bpc ? s->output_bpc : 10;
 	int ret;
 
+	if (old_state && old_state->self_refresh_active) {
+		drm_crtc_vblank_on(crtc);
+		rockchip_drm_set_win_enabled(crtc, true);
+		return;
+	}
+
 	mutex_lock(&vop->vop_lock);
 
 	WARN_ON(vop->event);