linux-kernel - Re: [PATCH V4 3/3] pwm: pxa: add device tree support

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Date:	Mon, 13 May 2013 14:20:43 +0800
From:	Eric Miao <eric.y.miao@...il.com>
To:	Chao Xie <xiechao.mail@...il.com>
Cc:	Chao Xie <chao.xie@...vell.com>,
	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 3/3] pwm: pxa: add device tree support

On Mon, May 13, 2013 at 1:04 PM, Chao Xie <xiechao.mail@...il.com> wrote:
>>> +       const struct of_device_id *of_id =
>>> +                       of_match_device(pxa_pwm_of_match, &pdev->dev);
>>> +       unsigned int npwm;
>>> +
>>> +       if (!of_id)
>>> +               return -ENODEV;
>>> +
>>> +       npwm = (unsigned int)of_id->data;
>>> +       pwm->chip.npwm = (npwm & HAS_SECONDARY_PWM) ? 2 : 1;
>>> +
>>> +       return 0;
>>> +}
>>> +
>>>  static int pwm_probe(struct platform_device *pdev)
>>>  {
>>>         const struct platform_device_id *id = platform_get_device_id(pdev);
>>> @@ -144,7 +180,6 @@ static int pwm_probe(struct platform_device *pdev)
>>>         pwm->chip.dev = &pdev->dev;
>>>         pwm->chip.ops = &pxa_pwm_ops;
>>>         pwm->chip.base = -1;
>>> -       pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
>>>
>>>         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>         if (r == NULL) {
>>> @@ -156,6 +191,20 @@ static int pwm_probe(struct platform_device *pdev)
>>>         if (IS_ERR(pwm->mmio_base))
>>>                 return PTR_ERR(pwm->mmio_base);
>>>
>>> +       if (!id) {
>>> +               if (IS_ENABLED(CONFIG_OF))
>>> +                       ret = pxa_pwm_parse_data_dt(pdev, pwm);
>>> +               else
>>> +                       ret = -ENODEV;
>>> +       } else {
>>> +               pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
>>> +       }
>>
>> ^^ braces not necessarily here, and I'm not really sure if we should check
>> CONFIG_OF firstly, and leave the platform_device_id thing as a legacy
>> fall back, what do you think?
>>
>>   if (IS_ENABLED(CONFIG_OF)) {
>>      ...
>>   } else {
>>     const struct platform_device_id *id = platform_get_device_id(...);
>>     ...
>>   }
>>
> it has some reasons.
> You ways works for
>      1. PWM defined in DT configuration file and CONFIG_OF is defined
>      2. CONFIG_OF is not defined.
> If COFNIG_OF is defined, but PWM is not defined in device tree
> configuration file. The device
> can still match the driver is the id_table is matched or name is matched.
> So I covered addtional situation
>     1. PWM is not defined in DT configuration file but CONFIG_OF is defined.
>
> So i keep the possiblility that event CONFIG_OF is defined, but PWM is
> not defined in DT file, and we still can use old way to probe the
> device.
>

Yeah I was thinking maybe we should not keep the legacy working if
CONFIG_OF is defined, but that should be OK:

Acked-by: Eric Miao <eric.y.miao@...il.com>

>>> +
>>> +       if (ret) {
>>> +               dev_err(&pdev->dev, "failed to parse data from device id\n");
>>> +               return ret;
>>> +       }
>>> +
>>>         ret = pwmchip_add(&pwm->chip);
>>>         if (ret < 0) {
>>>                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
>>> @@ -181,6 +230,7 @@ static struct platform_driver pwm_driver = {
>>>         .driver         = {
>>>                 .name   = "pxa25x-pwm",
>>>                 .owner  = THIS_MODULE,
>>> +               .of_match_table = pxa_pwm_of_match,
>>>         },
>>>         .probe          = pwm_probe,
>>>         .remove         = pwm_remove,
>>> --
>>> 1.7.4.1
>>>
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