Hi Bhuvanchandra,
> From: Lothar Wassmann <l...@karo-electronics.de>
>
> Change the pwm chip driver registration, so that a chip driver that
> supports polarity inversion can still be used with DTBs that don't
> provide the 'PWM_POLARITY' flag.
>
> This is done to provide polarity inversion support for the pwm-imx
> driver without having to modify all existing DTS files.
>
> Signed-off-by: Lothar Wassmann <l...@karo-electronics.de>
> Signed-off-by: Bhuvanchandra DV <bhuvanchandra...@toradex.com>
> Suggested-by: Thierry Reding <thierry.red...@gmail.com>
> ---
> drivers/pwm/core.c | 27 ++++++++++++++++-----------
> 1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index 195373e..aae8db3 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -137,9 +137,14 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc,
> const struct of_phandle_args *args) {
> struct pwm_device *pwm;
>
> + /* check, whether the driver supports a third cell for flags
> */ if (pc->of_pwm_n_cells < 3)
> return ERR_PTR(-EINVAL);
>
> + /* flags in the third cell are optional */
> + if (args->args_count < 2)
> + return ERR_PTR(-EINVAL);
> +
> if (args->args[0] >= pc->npwm)
> return ERR_PTR(-EINVAL);
>
> @@ -149,10 +154,12 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc,
> const struct of_phandle_args *args)
> pwm->args.period = args->args[1];
>
> - if (args->args[2] & PWM_POLARITY_INVERTED)
> - pwm->args.polarity = PWM_POLARITY_INVERSED;
> - else
> - pwm->args.polarity = PWM_POLARITY_NORMAL;
> + if (args->args_count > 2) {
> + if (args->args[2] & PWM_POLARITY_INVERTED)
> + pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
^^^^^^^^^^^^^^^^
here we should set pwm->args.polarity, since
the pwm_set_polarity() calls pwm_apply_state()
which requires duty_cycle and period to be set.
In this particular moment it is not yet set and
polarity is not properly configured.
Patch fixing this will be sent as a reply to this e-mail. Please just
squash it and test on your platform.
Best regards,
Łukasz Majewski
> + else
> + pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
> + }
>
> return pwm;
> }
> @@ -163,9 +170,14 @@ of_pwm_simple_xlate(struct pwm_chip *pc, const
> struct of_phandle_args *args) {
> struct pwm_device *pwm;
>
> + /* sanity check driver support */
> if (pc->of_pwm_n_cells < 2)
> return ERR_PTR(-EINVAL);
>
> + /* all cells are required */
> + if (args->args_count != pc->of_pwm_n_cells)
> + return ERR_PTR(-EINVAL);
> +
> if (args->args[0] >= pc->npwm)
> return ERR_PTR(-EINVAL);
>
> @@ -672,13 +684,6 @@ struct pwm_device *of_pwm_get(struct device_node
> *np, const char *con_id) goto put;
> }
>
> - if (args.args_count != pc->of_pwm_n_cells) {
> - pr_debug("%s: wrong #pwm-cells for %s\n",
> np->full_name,
> - args.np->full_name);
> - pwm = ERR_PTR(-EINVAL);
> - goto put;
> - }
> -
> pwm = pc->of_xlate(pc, &args);
> if (IS_ERR(pwm))
> goto put;
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