linux-kernel - Re: How to set fops in "struct platform_pwm_backlight

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Message-ID: <5265E5E6.30908@gmail.com>
Date:	Tue, 22 Oct 2013 10:41:42 +0800
From:	Mark Zhang <nvmarkzhang@...il.com>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	rpurdie@...ys.net, jg1.han@...sung.com,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	tomi.valkeinen@...com, linux-pwm@...r.kernel.org,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: How to set fops in "struct platform_pwm_backlight_data"?

Ping Thierry...

Mark
On 10/18/2013 12:48 PM, Mark Zhang wrote:
> On 10/17/2013 03:14 PM, Thierry Reding wrote:
>> On Thu, Oct 17, 2013 at 02:49:57PM +0800, Mark Zhang wrote:
>>> Hi,
>>>
>>> This is the first time I send mail to linux-pwm, I didn't read through
>>> the mails in this list, so if somebody already asked this question, I'm
>>> sorry about that.
>>>
>>> I wanna set some fops in "struct platform_pwm_backlight_data". But the
>>> currrent probe function in pwm_bl.c says:
>>>
>>> -------
>>> if (!data) {
>>> 	ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
>>> 	if (ret < 0) {
>>> 		dev_err(&pdev->dev, "failed to find platform data\n");
>>> 		return ret;
>>> 	}
>>>
>>> 	data = &defdata;
>>> }
>>> -------
>>>
>>> This looks like if we set the platform data for pwm backlight device,
>>> "pwm_backlight_parse_dt" will never have a chance to be called, which
>>> means the stuffs I defined in backlight DT node will be ignored.
>>>
>>> If I don't set the platform data for pwm backlight device, according to
>>> the pwm_backlight_probe, I will never have a chance to set some fops
>>> which I need(like "notify", "check_fb"...).
>>>
>>> So, what I suppose to do now? Maybe there is a way to set function
>>> pointers in DT?
>>
>> Perhaps you could describe in more detail what you need the functions
>> for.
>>
> 
> Okay, I just want to set the "notify" function pointer in "struct
> platform_pwm_backlight_data", because I want to tune the brightness
> value before the pwm-bl sets the brightness to hardware. I don't know
> how to do that, unless we define the platform data explicitly.
> 
> Mark
>> Generally you're not supposed to mix DT and platform data. Without more
>> info that's about all I can say.
>>
>> Thierry
>>
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