linux-kernel - [PATCH 5.3 028/135] clk: at91: avoid sleeping early

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Date:   Tue,  3 Dec 2019 23:34:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.3 028/135] clk: at91: avoid sleeping early

From: Alexandre Belloni <alexandre.belloni@...tlin.com>

[ Upstream commit 658fd65cf0b0d511de1718e48d9a28844c385ae0 ]

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@...gutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.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@...gutronix.de>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/at91/clk-main.c |  5 ++++-
 drivers/clk/at91/sckc.c     | 20 ++++++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
index 311cea0c3ae2b..54b2b2dd2bb57 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 9bfe9a28294a7..fac0ca56d42d9 100644
--- a/drivers/clk/at91/sckc.c
+++ b/drivers/clk/at91/sckc.c
@@ -76,7 +76,10 @@ static int clk_slow_osc_prepare(struct clk_hw *hw)
 
 	writel(tmp | osc->bits->cr_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;
 }
@@ -187,7 +190,10 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
 
 	writel(readl(sckcr) | osc->bits->cr_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;
 }
@@ -288,7 +294,10 @@ 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;
 }
@@ -533,7 +542,10 @@ 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;
-- 
2.20.1