linux-kernel - Re: [PATCH 2/2] hid: add PM support to PicoLCD device

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Date:	Tue, 27 Apr 2010 22:16:48 +0200
From:	Bruno Prémont <bonbons@...ux-vserver.org>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Oliver Neukum <oliver@...kum.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Nicu Pavel <npavel@...ner.com>,
	Jaya Kumar <jayakumar.lkml@...il.com>,
	"Rick L. Vinyard Jr." <rvinyard@...nmsu.edu>
Subject: Re: [PATCH 2/2] hid: add PM support to PicoLCD device

On Tue, 27 April 2010 Jiri Kosina <jkosina@...e.cz> wrote:
> On Sun, 25 Apr 2010, Bruno Prémont wrote:
> 
> > Add PM support in order to turn off backlight on suspend, restore
> > it on resume and especially restore complete state on reset-resume.
> > 
> > Signed-off-by: Bruno Prémont <bonbons@...ux-vserver.org>
> > ---
> >  drivers/hid/hid-picolcd.c |   61 +++++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 61 insertions(+), 0 deletions(-)
> > 
> > diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
> > index aa6f2e1..c652390 100644
> > --- a/drivers/hid/hid-picolcd.c
> > +++ b/drivers/hid/hid-picolcd.c
> > @@ -852,6 +852,20 @@ static inline int picolcd_resume_backlight(struct picolcd_data *data)
> >  	return picolcd_set_brightness(data->backlight);
> >  }
> >  
> > +#ifdef CONFIG_PM
> > +static void picolcd_suspend_backlight(struct picolcd_data *data)
> > +{
> > +	int bl_power = data->lcd_power;
> > +	if (!data->backlight)
> > +		return;
> > +
> > +	data->backlight->props.power = FB_BLANK_POWERDOWN;
> > +	picolcd_set_brightness(data->backlight);
> > +	data->lcd_power = data->backlight->props.power = bl_power;
> > +}
> > +#else
> > +#define picolcd_suspend_backlight(a)
> > +#endif /* CONFIG_PM */
> 
> Stylistic thing -- it would be nice if this was actually 
> 
> static inline void picolcd_suspend_backlight(struct picolcd_data *data)
> {
> 	return 0;
> }
> 
> But why do you need to have it defined in !CONFIG_PM situation anyway? 
> It's not used otherwise at all.

Yeah, I could drop the #else branch (of #ifconfig CONFIG_PM).

Is gcc quiet about defined but unused static inline functions?
It's in order to avoid those warnings that I used #define bla().
(same in other occasions of stubs returning void.

Might be I forgot the inline keyword for the case I got the warning
about defined but unused function. Will check tomorrow.

> >  #else
> >  static inline int picolcd_init_backlight(struct picolcd_data *data,
> >  		struct hid_report *report)
> > @@ -865,6 +879,7 @@ static inline int picolcd_resume_backlight(struct picolcd_data *data)
> >  {
> >  	return 0;
> >  }
> > +#define picolcd_suspend_backlight(a)
> 
> Any why is it defined once more here?

Thats in the case where CONFIG_HID_PICOLCD_BACKLIGHT is not defined.
c.f. the #else at the beginning of this quote.


Thanks,
Bruno
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