Commit 658fd65c authored by Alexandre Belloni's avatar Alexandre Belloni Committed by Stephen Boyd
Browse files

clk: at91: avoid sleeping early 



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: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lkml.kernel.org/r/20190920153906.20887-1-alexandre.belloni@bootlin.com


Fixes: 80eded6c ("clk: at91: add slow clks driver")
Tested-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent b234fe95

drivers/clk/at91/clk-main.c

+4 −1
Original line number Diff line number Diff line
@@ -297,6 +297,9 @@ static int clk_main_probe_frequency(struct regmap *regmap) 
		regmap_read(regmap, AT91_CKGR_MCFR, &mcfr);

		if (mcfr & AT91_PMC_MAINRDY)

			return 0;

		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));

drivers/clk/at91/sckc.c

+16 −4
Original line number Diff line number Diff line
@@ -76,6 +76,9 @@ static int clk_slow_osc_prepare(struct clk_hw *hw) 


	writel(tmp | osc->bits->cr_osc32en, sckcr);



	if (system_state < SYSTEM_RUNNING)

		udelay(osc->startup_usec);

	else

		usleep_range(osc->startup_usec, osc->startup_usec + 1);



	return 0;
@@ -187,6 +190,9 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw) 


	writel(readl(sckcr) | osc->bits->cr_rcen, sckcr);



	if (system_state < SYSTEM_RUNNING)

		udelay(osc->startup_usec);

	else

		usleep_range(osc->startup_usec, osc->startup_usec + 1);



	return 0;
@@ -288,6 +294,9 @@ static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index) 


	writel(tmp, sckcr);



	if (system_state < SYSTEM_RUNNING)

		udelay(SLOWCK_SW_TIME_USEC);

	else

		usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);



	return 0;
@@ -533,6 +542,9 @@ static int clk_sama5d4_slow_osc_prepare(struct clk_hw *hw) 
		return 0;

	}



	if (system_state < SYSTEM_RUNNING)

		udelay(osc->startup_usec);

	else

		usleep_range(osc->startup_usec, osc->startup_usec + 1);

	osc->prepared = true;

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