linux-kernel - Re: [PATCH] leds: leds-pwm: Convert to use devm_get

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Date:	Mon, 12 Nov 2012 09:40:56 +0100
From:	Péter Ujfalusi <peter.ujfalusi@...com>
To:	Bryan Wu <cooloney@...il.com>
CC:	Richard Purdie <rpurdie@...ys.net>,
	Luotao Fu <l.fu@...gutronix.de>, <linux-leds@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] leds: leds-pwm: Convert to use devm_get_pwm

On 11/10/2012 02:48 AM, Bryan Wu wrote:
> On Wed, Nov 7, 2012 at 3:42 AM, Peter Ujfalusi <peter.ujfalusi@...com> wrote:
>> Update the driver to use the new API for requesting pwm so we can take
>> advantage of the pwm_lookup table to find the correct pwm to be used for the
>> LED functionality.
>> If the devm_get_pwm fails we fall back to legacy mode to try to get the pwm.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
>> ---
>>  drivers/leds/leds-pwm.c | 16 ++++++++++++++--
>>  1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
>> index f2e44c7..6bf9445 100644
>> --- a/drivers/leds/leds-pwm.c
>> +++ b/drivers/leds/leds-pwm.c
>> @@ -47,6 +47,19 @@ static void led_pwm_set(struct led_classdev *led_cdev,
>>         }
>>  }
>>
>> +static struct pwm_device *led_pwm_request_pwm(struct platform_device *pdev,
>> +                                             struct led_pwm *cur_led)
>> +{
>> +       struct pwm_device *pwm;
>> +
>> +       pwm = devm_pwm_get(&pdev->dev, cur_led->name);
>> +       if (IS_ERR(pwm)) {
>> +               dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
>> +               pwm = pwm_request(cur_led->pwm_id, cur_led->name);
> 
> Looks good, but why we still need to keep the old API pwm_request(),
> if devm_pwm_get() is the right replacement. AFAIK, devm_***() API will
> help to clean up if device probing fails.
> 
> So if it is good enough, we can just replace pwm_request() to the devm_pwm_get()

I have greped for "leds_pwm" in arch/ and the only place it is used is the
arch/arm/mach-omap2/board-sdp4430sdp.c and that is not working at all (using
wrong ID for the PWM).
I think I can remove the legacy way of requesting the pwm from the driver
safely (I can also mark the pwm_id in struct led_pwm as deprecated at the same
time).
Will send the v2 soon.

Thank you,
Péter

> 
> Thanks,
> -Bryan
> 
>> +       }
>> +       return pwm;
>> +}
>> +
>>  static int led_pwm_probe(struct platform_device *pdev)
>>  {
>>         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
>> @@ -67,8 +80,7 @@ static int led_pwm_probe(struct platform_device *pdev)
>>                 cur_led = &pdata->leds[i];
>>                 led_dat = &leds_data[i];
>>
>> -               led_dat->pwm = pwm_request(cur_led->pwm_id,
>> -                               cur_led->name);
>> +               led_dat->pwm = led_pwm_request_pwm(pdev, cur_led);
>>                 if (IS_ERR(led_dat->pwm)) {
>>                         ret = PTR_ERR(led_dat->pwm);
>>                         dev_err(&pdev->dev, "unable to request PWM %d\n",
>> --
>> 1.8.0
>>


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