diff mbox

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

Message ID 1464942192-25967-9-git-send-email-boris.brezillon@free-electrons.com (mailing list archive)
State New, archived
Headers show

Commit Message

Boris BREZILLON June 3, 2016, 8:23 a.m. UTC
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 | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

Comments

Brian Norris June 3, 2016, 8:38 p.m. UTC | #1
On Fri, Jun 03, 2016 at 10:23:06AM +0200, Boris Brezillon wrote:
> 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 | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
> index 6300d3e..8232c5b 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 +409,19 @@ 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++) {
> +		struct pwm_state state;
> +
> +		pwm_get_state(&pc->chip.pwms[i], &state);
> +		if (state.enabled)

Similar to pwm-rockchip: you could just do if (pwm_is_enabled(...)).

Brian

> +			clk_enable(pc->clk);
> +	}
> +	clk_disable(pc->clk);
> +
>  	platform_set_drvdata(pdev, pc);
>  
>  	return 0;
> -- 
> 2.7.4
>
diff mbox

Patch

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 6300d3e..8232c5b 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 +409,19 @@  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++) {
+		struct pwm_state state;
+
+		pwm_get_state(&pc->chip.pwms[i], &state);
+		if (state.enabled)
+			clk_enable(pc->clk);
+	}
+	clk_disable(pc->clk);
+
 	platform_set_drvdata(pdev, pc);
 
 	return 0;