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[PATCH v3 08/14] pwm: sti: Avoid glitches on already running PWMs

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The current logic will disable the PWM clk even if a PWM was left
enabled by the bootloader (because it's controlling a critical device
like a regulator for example).
Keep the PWM clk enabled if at least one PWM is enabled to avoid any
glitches.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
 drivers/pwm/pwm-sti.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 6300d3e..5bda51d 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -340,7 +340,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	struct sti_pwm_compat_data *cdata;
 	struct sti_pwm_chip *pc;
 	struct resource *res;
-	int ret;
+	int i, ret;
 
 	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)
@@ -391,7 +391,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	ret = clk_prepare(pc->clk);
+	ret = clk_prepare_enable(pc->clk);
 	if (ret) {
 		dev_err(dev, "failed to prepare clock\n");
 		return ret;
@@ -409,6 +409,16 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/*
+	 * Keep the PWM clk enabled if some PWMs appear to be up and
+	 * running.
+	 */
+	for (i = 0; i < pc->chip.npwm; i++) {
+		if (pwm_is_enabled(&pc->chip.pwms[i]))
+			clk_enable(pc->clk);
+	}
+	clk_disable(pc->clk);
+
 	platform_set_drvdata(pdev, pc);
 
 	return 0;
-- 
2.7.4

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[PATCH v3 00/14] regulator: pwm: various improvements Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 04/14] pwm: rockchip: Add support for hardware readout Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 05/14] pwm: rockchip: Avoid glitches on already running PWMs Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 09/14] regulator: pwm: Adjust PWM config at probe time Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 02/14] pwm: Add two helpers to ease relative duty cycle manipulation Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 08/14] pwm: sti: Avoid glitches on already running PWMs Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 13/14] regulator: pwm: Support extra continuous mode cases Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200
  [PATCH v3 03/14] pwm: rockchip: Fix period and duty_cycle approximation Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-06-14 11:20 +0200

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