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SubjectRe: [PATCH v2 2/3] pwm: stm32: split breakinput apply routine to ease PM support
On Fri, Oct 04, 2019 at 02:53:52PM +0200, Fabrice Gasnier wrote:
> Split breakinput routine that configures STM32 timers 'break' safety
> feature upon probe, into two routines:
> - stm32_pwm_apply_breakinputs() sets all the break inputs into registers.
> - stm32_pwm_probe_breakinputs() probes the device tree break input settings
> before calling stm32_pwm_apply_breakinputs()
>
> This is a precursor patch to ease PM support. Registers content may get
> lost during low power. So, break input settings applied upon probe need
> to be restored upon resume (e.g. by calling stm32_pwm_apply_breakinputs()).
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
> drivers/pwm/pwm-stm32.c | 48 ++++++++++++++++++++++++++++--------------------
> 1 file changed, 28 insertions(+), 20 deletions(-)

Applied, thanks. I've made some minor changes, mostly for consistency
with other drivers and the PWM core. See below.

> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
> index 359b085..cf8658c 100644
> --- a/drivers/pwm/pwm-stm32.c
> +++ b/drivers/pwm/pwm-stm32.c
> @@ -19,6 +19,12 @@
> #define CCMR_CHANNEL_MASK 0xFF
> #define MAX_BREAKINPUT 2
>
> +struct stm32_breakinput {
> + u32 index;
> + u32 level;
> + u32 filter;
> +};
> +
> struct stm32_pwm {
> struct pwm_chip chip;
> struct mutex lock; /* protect pwm config/enable */
> @@ -26,15 +32,11 @@ struct stm32_pwm {
> struct regmap *regmap;
> u32 max_arr;
> bool have_complementary_output;
> + struct stm32_breakinput breakinput[MAX_BREAKINPUT];
> + unsigned int nbreakinput;

I changed these to breakinputs and num_breakinputs since they are
slightly more consistent with the naming elsewhere in PWM.

> u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */
> };
>
> -struct stm32_breakinput {
> - u32 index;
> - u32 level;
> - u32 filter;
> -};
> -
> static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
> {
> return container_of(chip, struct stm32_pwm, chip);
> @@ -512,15 +514,27 @@ static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
> return (bdtr & bke) ? 0 : -EINVAL;
> }
>
> -static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
> +static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv)
> +{
> + int i, ret = 0;

Made i unsigned int.

> +
> + for (i = 0; i < priv->nbreakinput && !ret; i++) {
> + ret = stm32_pwm_set_breakinput(priv,
> + priv->breakinput[i].index,
> + priv->breakinput[i].level,
> + priv->breakinput[i].filter);
> + }

I thought this was a little odd, so I changed it to explicitly check the
value of ret and return on error.

> +
> + return ret;

And then this became "return 0;"

> +}
> +
> +static int stm32_pwm_probe_breakinputs(struct stm32_pwm *priv,
> struct device_node *np)
> {
> - struct stm32_breakinput breakinput[MAX_BREAKINPUT];
> - int nb, ret, i, array_size;
> + int nb, ret, array_size;
>
> nb = of_property_count_elems_of_size(np, "st,breakinput",
> sizeof(struct stm32_breakinput));
> -

Dropped this since it made the code look cluttered.

Thierry

> /*
> * Because "st,breakinput" parameter is optional do not make probe
> * failed if it doesn't exist.
> @@ -531,20 +545,14 @@ static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
> if (nb > MAX_BREAKINPUT)
> return -EINVAL;
>
> + priv->nbreakinput = nb;
> array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
> ret = of_property_read_u32_array(np, "st,breakinput",
> - (u32 *)breakinput, array_size);
> + (u32 *)priv->breakinput, array_size);
> if (ret)
> return ret;
>
> - for (i = 0; i < nb && !ret; i++) {
> - ret = stm32_pwm_set_breakinput(priv,
> - breakinput[i].index,
> - breakinput[i].level,
> - breakinput[i].filter);
> - }
> -
> - return ret;
> + return stm32_pwm_apply_breakinputs(priv);
> }
>
> static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
> @@ -614,7 +622,7 @@ static int stm32_pwm_probe(struct platform_device *pdev)
> if (!priv->regmap || !priv->clk)
> return -EINVAL;
>
> - ret = stm32_pwm_apply_breakinputs(priv, np);
> + ret = stm32_pwm_probe_breakinputs(priv, np);
> if (ret)
> return ret;
>
> --
> 2.7.4
>
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