On 11/08/2015 at 15:40:45 +0200, Daniel Lezcano wrote :

On 08/11/2015 11:38 AM, Alexandre Belloni wrote:

quoted

From: Boris Brezillon <redacted>

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the timer counters.

Signed-off-by: Boris Brezillon <redacted>
Signed-off-by: Alexandre Belloni <redacted>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Cc: Daniel Lezcano <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Thierry Reding <redacted>
Cc: linux-pwm at vger.kernel.org

 drivers/clocksource/tcb_clksrc.c |  8 ++++++++
 drivers/misc/atmel_tclib.c       |  4 ++++
 drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
 include/linux/atmel_tc.h         |  1 +
 4 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index b9b7277173c2..969ba03633b0 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c

@@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
 	ret = clk_prepare_enable(t2_clk);
 	if (ret)
 		return ret;
+
+	ret = clk_prepare_enable(tc->slow_clk);
+	if (ret) {
+		clk_disable_unprepare(t2_clk);
+		return ret;
+	}
+
 	clk_disable(t2_clk);

Do you need t2_clk to be enabled in order to enable tc->slow_clk ?

No, I'll move clk_prepare_enable for tc->slow_clk before t2_clk.

quoted

+
+err_free_tc:
+	atmel_tc_free(tc);
+
+	return err;

What about clk_unprepare_disable(tc->slow_clk) ?

Indeed, I trusted Boris a bit too much ;)

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com