From 6ac1571b4c60cb73a1f174b15ea93f7e38d74a88 Mon Sep 17 00:00:00 2001
From: Dmitry Osipenko <digetx@gmail.com>
Date: Thu, 15 Jun 2017 02:18:29 +0300
Subject: [PATCH] drm/tegra: dc: Avoid reset asserts on Tegra20
Git-commit: 6ac1571b4c60cb73a1f174b15ea93f7e38d74a88
Patch-mainline: 4.13-rc1
References: bsc#1051510

Commit 33a8eb8d40ee ("drm/tegra: dc: Implement runtime PM") introduced
HW reset control. It causes a hang on Tegra20 if both display
controllers are utilized (RGB panel and HDMI). The TRM suggests that
each display controller has its own reset control, apparently it is not
correct.

Fixes: 33a8eb8d40ee ("drm/tegra: dc: Implement runtime PM")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/tegra/dc.c |   30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -30,6 +30,7 @@ struct tegra_dc_soc_info {
 	bool supports_block_linear;
 	unsigned int pitch_align;
 	bool has_powergate;
+	bool broken_reset;
 };
 
 struct tegra_plane {
@@ -1856,6 +1857,7 @@ static const struct tegra_dc_soc_info te
 	.supports_block_linear = false,
 	.pitch_align = 8,
 	.has_powergate = false,
+	.broken_reset = true,
 };
 
 static const struct tegra_dc_soc_info tegra30_dc_soc_info = {
@@ -1865,6 +1867,7 @@ static const struct tegra_dc_soc_info te
 	.supports_block_linear = false,
 	.pitch_align = 8,
 	.has_powergate = false,
+	.broken_reset = false,
 };
 
 static const struct tegra_dc_soc_info tegra114_dc_soc_info = {
@@ -1874,6 +1877,7 @@ static const struct tegra_dc_soc_info te
 	.supports_block_linear = false,
 	.pitch_align = 64,
 	.has_powergate = true,
+	.broken_reset = false,
 };
 
 static const struct tegra_dc_soc_info tegra124_dc_soc_info = {
@@ -1883,6 +1887,7 @@ static const struct tegra_dc_soc_info te
 	.supports_block_linear = true,
 	.pitch_align = 64,
 	.has_powergate = true,
+	.broken_reset = false,
 };
 
 static const struct tegra_dc_soc_info tegra210_dc_soc_info = {
@@ -1892,6 +1897,7 @@ static const struct tegra_dc_soc_info te
 	.supports_block_linear = true,
 	.pitch_align = 64,
 	.has_powergate = true,
+	.broken_reset = false,
 };
 
 static const struct of_device_id tegra_dc_of_match[] = {
@@ -1989,7 +1995,8 @@ static int tegra_dc_probe(struct platfor
 		return PTR_ERR(dc->rst);
 	}
 
-	reset_control_assert(dc->rst);
+	if (!dc->soc->broken_reset)
+		reset_control_assert(dc->rst);
 
 	if (dc->soc->has_powergate) {
 		if (dc->pipe == 0)
@@ -2063,10 +2070,12 @@ static int tegra_dc_suspend(struct devic
 	struct tegra_dc *dc = dev_get_drvdata(dev);
 	int err;
 
-	err = reset_control_assert(dc->rst);
-	if (err < 0) {
-		dev_err(dev, "failed to assert reset: %d\n", err);
-		return err;
+	if (!dc->soc->broken_reset) {
+		err = reset_control_assert(dc->rst);
+		if (err < 0) {
+			dev_err(dev, "failed to assert reset: %d\n", err);
+			return err;
+		}
 	}
 
 	if (dc->soc->has_powergate)
@@ -2096,10 +2105,13 @@ static int tegra_dc_resume(struct device
 			return err;
 		}
 
-		err = reset_control_deassert(dc->rst);
-		if (err < 0) {
-			dev_err(dev, "failed to deassert reset: %d\n", err);
-			return err;
+		if (!dc->soc->broken_reset) {
+			err = reset_control_deassert(dc->rst);
+			if (err < 0) {
+				dev_err(dev,
+					"failed to deassert reset: %d\n", err);
+				return err;
+			}
 		}
 	}