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: 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>

diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
index 87083b3a2769d2f383f381a1f82cc219a6ac953e..37c22667e8319011aa5528613c26a9e0544e3e6e 100644 (file)
--- 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 9bfe9a28294a7ec7f5acbb38f7e21f477355839e..fac0ca56d42d92a3df623f2d3e69cb5ca380e639 100644 (file)
--- 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;