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SubjectRe: [PATCH v2 2/6] pwm: core: make the PWM_POLARITY flag in DTB optional
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Hi Lukasz,

On 10/06/16 12:06, Lukasz Majewski wrote:

> Hi Bhuvanchandra,
>
>> From: Lothar Wassmann <LW@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 <LW@KARO-electronics.de>
>> Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
>> Suggested-by: Thierry Reding <thierry.reding@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.

Agreed. Will do a clean v3 patchset along with the patch you sent
(pwm: core: Use pwm->args.polarity to setup PWM_POLARITY_INVERSED).

--
Bhuvan

>
> 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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