added brightness feature to lcd class.
in [Kernel]
|
From: Pavel Machek on 5 Nov 2009 14:30 On Mon 2009-11-02 17:50:02, InKi Dae wrote: > This patch adds brightness feature to lcd class. > (kernel/driver/video/backlight/lcd.c) > > In the past, most of the lcd panels for embedded system was TFT-LCD > Panel needing backlight device. > But now AMOLED LCD Panel appeared so we should consider brightness > control for AMOLED Panel. > > For the time being, I used backlight fake driver for brightness > control of AMOLED LCD Panel. > But this way is not good, so I propose to add brightness feature to lcd class. > Why is it 'not good'? Using backlight driver seems like way to go to me. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: InKi Dae on 7 Nov 2009 07:50 Thank you for your comments. using backlight is good way in case of TFT-LCD Panel. because TFT-LCD Panel needs backlight device to light up. but AMOLED LCD Panel doesn't need backlight device because lighting up itself. if you try to control brightness of AMOLED LCD Panel and using backlight class then you should write fake backlight driver that it has no real device for controlling and would control brightness through that driver. with this reason, I think that it's better to control brightness through lcd class in case of AMOLED LCD panel. If lcd class has birghtness feature then AMOLED LCD Panel driver would become more simple and effective. I think it is more generic way that only real device should have device driver so I proposed this. Thank you. Best Regards, InKi Dae. 2009/11/6 Pavel Machek <pavel(a)ucw.cz>: > On Mon 2009-11-02 17:50:02, InKi Dae wrote: >> This patch adds brightness feature to lcd class. >> (kernel/driver/video/backlight/lcd.c) >> >> In the past, most of the lcd panels for embedded system was TFT-LCD >> Panel needing backlight device. >> But now AMOLED LCD Panel appeared so we should consider brightness >> control for AMOLED Panel. >> >> For the time being, I used backlight fake driver for brightness >> control of AMOLED LCD Panel. >> But this way is not good, so I propose to add brightness feature to lcd class. >> > > Why is it 'not good'? Using backlight driver seems like way to go to > me. > > � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �Pavel > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Pavel Machek on 7 Nov 2009 11:50 On Sat 2009-11-07 21:43:50, InKi Dae wrote: > Thank you for your comments. > > using backlight is good way in case of TFT-LCD Panel. > because TFT-LCD Panel needs backlight device to light up. > > but AMOLED LCD Panel doesn't need backlight device because lighting up itself. I know. So what? User wants to set brightness. Why should userspace know/care if it is TFT or AMOLED? I have this script: #!/bin/bash echo $1 > /sys/class/backlight/*/brightness why should I have to rewrite it just because you decided amoled is special? Kernel is expected to provide hw abstraction... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: InKi Dae on 9 Nov 2009 10:40 are you saying me that user shouldn't know if it is TFT-LCD or AMOLD? I agree your saying. if lcd class has brightness feature then sysfs file for controlling brightness will be placed in /sys/class/lcd/*/brightness. it would be a problem because the path is no sysfs you expected. how about that symbolic link file is created by lcd class for user? like this, /sys/class/lcd/*/brightness -> /sys/class/backlight/*/brightness for this, some codes of creating symbolic link file should be added to lcd class. I still think it is not good way that lcd panel driver not having backlight device has backlight driver to control brightness and it should be solved in the course of time. thank you. 2009/11/8 Pavel Machek <pavel(a)ucw.cz>: > On Sat 2009-11-07 21:43:50, InKi Dae wrote: >> Thank you for your comments. >> >> using backlight is good way in case of TFT-LCD Panel. >> because TFT-LCD Panel needs backlight device to light up. >> >> but AMOLED LCD Panel doesn't need backlight device because lighting up itself. > > I know. So what? > > User wants to set brightness. Why should userspace know/care if it is > TFT or AMOLED? > > I have this script: > > #!/bin/bash > echo $1 > /sys/class/backlight/*/brightness > > why should I have to rewrite it just because you decided amoled is > special? > > Kernel is expected to provide hw abstraction... > > � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �Pavel > > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Pavel Machek on 9 Nov 2009 15:20 On Tue 2009-11-10 00:37:59, InKi Dae wrote: > are you saying me that user shouldn't know if it is TFT-LCD or AMOLD? > I agree your saying. Parse error. > if lcd class has brightness feature then sysfs file for controlling > brightness will be placed > in /sys/class/lcd/*/brightness. > it would be a problem because the path is no sysfs you expected. > > how about that symbolic link file is created by lcd class for user? > like this, > /sys/class/lcd/*/brightness -> /sys/class/backlight/*/brightness > The symlink would have to be backwards, but yes, that would be better than nothing. (But I still don't see why we should make it complex. Just pretend it is backlight.) Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|
Next
|
Last
Pages: 1 2 3 Prev: rt2x00: add driver private field to struct rt2x00_dev Next: Accessors for mm locking |