On Thu, Sep 23, 2021 at 09:12:24PM -0500, Bjorn Andersson wrote:
> The existing pxa driver and the upcoming addition of PWM support in the
> TI sn565dsi86 DSI/eDP bridge driver both has a single PWM channel and
> thereby a need for a of_xlate function with the period as its single
> argument.
>
> Introduce a common helper function in the core that can be used as
> of_xlate by such drivers and migrate the pxa driver to use this.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
>
> Changes since v4:
> - None
>
> drivers/pwm/core.c | 26 ++++++++++++++++++++++++++
> drivers/pwm/pwm-pxa.c | 16 +---------------
> include/linux/pwm.h | 2 ++
> 3 files changed, 29 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index 4527f09a5c50..2c6b155002a2 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -152,6 +152,32 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
> }
> EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
>
> +struct pwm_device *
> +of_pwm_single_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
> +{
> + struct pwm_device *pwm;
> +
> + if (pc->of_pwm_n_cells < 1)
> + return ERR_PTR(-EINVAL);
> +
> + /* validate that one cell is specified, optionally with flags */
> + if (args->args_count != 1 && args->args_count != 2)
> + return ERR_PTR(-EINVAL);
> +
> + pwm = pwm_request_from_chip(pc, 0, NULL);
> + if (IS_ERR(pwm))
> + return pwm;
> +
> + pwm->args.period = args->args[0];
> + pwm->args.polarity = PWM_POLARITY_NORMAL;
> +
> + if (args->args_count == 2 && args->args[2] & PWM_POLARITY_INVERTED)
> + pwm->args.polarity = PWM_POLARITY_INVERSED;
of_pwm_xlate_with_flags is a bit more complicated. Translating
accordingly this would yield:
if (pc->of_pwm_n_cells >= 2) {
if (args->args_count > 1 && args->args[1] & PWM_POLARITY_INVERTED)
pwm->args.polarity = PWM_POLARITY_INVERSED;
}
Given that pc->of_pwm_n_cells isn't used when a phandle is parsed (in
of_pwm_get()) I think your variant is fine.
So I think technically the patch is good, for me the question is if we
want to make new drivers of_pwm_xlate_with_flags for consistency even
though this would mean that the first argument has to be 0 for all
phandles. Thierry? Lee?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
Attachment:
signature.asc
Description: PGP signature
