release/5.2.30/clk-at91-avoid-sleeping-early.patch

From db31f87a36c613de77ea50a58324cc2b3cd232b4 Mon Sep 17 00:00:00 2001
From: Alexandre Belloni <alexandre.belloni@bootlin.com>
Date: Fri, 20 Sep 2019 17:39:06 +0200
Subject: [PATCH] clk: at91: avoid sleeping early
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commit 658fd65cf0b0d511de1718e48d9a28844c385ae0 upstream.

It is not allowed to sleep to early in the boot process and this may lead
to kernel issues if the bootloader didn't prepare the slow clock and main
clock.

This results in the following error and dump stack on the AriettaG25:
   bad: scheduling from the idle thread!

Ensure it is possible to sleep, else simply have a delay.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lkml.kernel.org/r/20190920153906.20887-1-alexandre.belloni@bootlin.com
Fixes: 80eded6ce8bb ("clk: at91: add slow clks driver")
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
index 311cea0c3ae2..54b2b2dd2bb5 100644
--- a/drivers/clk/at91/clk-main.c
+++ b/drivers/clk/at91/clk-main.c
@@ -297,7 +297,10 @@ static int clk_main_probe_frequency(struct regmap *regmap)
 		regmap_read(regmap, AT91_CKGR_MCFR, &mcfr);
 		if (mcfr & AT91_PMC_MAINRDY)
 			return 0;
-		usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT);
+		if (system_state < SYSTEM_RUNNING)
+			udelay(MAINF_LOOP_MIN_WAIT);
+		else
+			usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT);
 	} while (time_before(prep_time, timeout));
 
 	return -ETIMEDOUT;
diff --git a/drivers/clk/at91/sckc.c b/drivers/clk/at91/sckc.c
index 45526f56f1ba..155cad28af36 100644
--- a/drivers/clk/at91/sckc.c
+++ b/drivers/clk/at91/sckc.c
@@ -69,7 +69,10 @@ static int clk_slow_osc_prepare(struct clk_hw *hw)
 
 	writel(tmp | AT91_SCKC_OSC32EN, sckcr);
 
-	usleep_range(osc->startup_usec, osc->startup_usec + 1);
+	if (system_state < SYSTEM_RUNNING)
+		udelay(osc->startup_usec);
+	else
+		usleep_range(osc->startup_usec, osc->startup_usec + 1);
 
 	return 0;
 }
@@ -170,7 +173,10 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
 
 	writel(readl(sckcr) | AT91_SCKC_RCEN, sckcr);
 
-	usleep_range(osc->startup_usec, osc->startup_usec + 1);
+	if (system_state < SYSTEM_RUNNING)
+		udelay(osc->startup_usec);
+	else
+		usleep_range(osc->startup_usec, osc->startup_usec + 1);
 
 	return 0;
 }
@@ -261,7 +267,10 @@ static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index)
 
 	writel(tmp, sckcr);
 
-	usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);
+	if (system_state < SYSTEM_RUNNING)
+		udelay(SLOWCK_SW_TIME_USEC);
+	else
+		usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);
 
 	return 0;
 }
@@ -398,7 +407,10 @@ static int clk_sama5d4_slow_osc_prepare(struct clk_hw *hw)
 		return 0;
 	}
 
-	usleep_range(osc->startup_usec, osc->startup_usec + 1);
+	if (system_state < SYSTEM_RUNNING)
+		udelay(osc->startup_usec);
+	else
+		usleep_range(osc->startup_usec, osc->startup_usec + 1);
 	osc->prepared = true;
 
 	return 0;
-- 
2.7.4