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

Brian Norris
2016-06-03T20:38:48Z

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
>