drm/tegra: dc: Extend debug stats with total number of events

It's useful to know the total number of underflow events and currently
the debug stats are getting reset each time CRTC is being disabled. Let's
account the overall number of events that doesn't get a reset.
Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/dc.c

@@ -1602,6 +1602,11 @@ static int tegra_dc_show_stats(struct seq_file *s, void *data)
 	seq_printf(s, "underflow: %lu\n", dc->stats.underflow);
 	seq_printf(s, "overflow: %lu\n", dc->stats.overflow);
 
+	seq_printf(s, "frames total: %lu\n", dc->stats.frames_total);
+	seq_printf(s, "vblank total: %lu\n", dc->stats.vblank_total);
+	seq_printf(s, "underflow total: %lu\n", dc->stats.underflow_total);
+	seq_printf(s, "overflow total: %lu\n", dc->stats.overflow_total);
+
 	return 0;
 }
 
@@ -2368,6 +2373,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): frame end\n", __func__);
 		*/
+		dc->stats.frames_total++;
 		dc->stats.frames++;
 	}
 
@@ -2376,6 +2382,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		dev_dbg(dc->dev, "%s(): vertical blank\n", __func__);
 		*/
 		drm_crtc_handle_vblank(&dc->base);
+		dc->stats.vblank_total++;
 		dc->stats.vblank++;
 	}
 
@@ -2383,6 +2390,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): underflow\n", __func__);
 		*/
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 
@@ -2390,11 +2398,13 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): overflow\n", __func__);
 		*/
+		dc->stats.overflow_total++;
 		dc->stats.overflow++;
 	}
 
 	if (status & HEAD_UF_INT) {
 		dev_dbg_ratelimited(dc->dev, "%s(): head underflow\n", __func__);
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 

drivers/gpu/drm/tegra/dc.h

@@ -46,6 +46,11 @@ struct tegra_dc_stats {
 	unsigned long vblank;
 	unsigned long underflow;
 	unsigned long overflow;
+
+	unsigned long frames_total;
+	unsigned long vblank_total;
+	unsigned long underflow_total;
+	unsigned long overflow_total;
 };
 
 struct tegra_windowgroup_soc {