added brightness feature to lcd class.
in [Kernel]
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From: InKi Dae on 11 Nov 2009 01:20 it's my comment below. thank you. 2009/11/10 Richard Purdie <rpurdie(a)linux.intel.com>: > On Tue, 2009-11-10 at 12:26 +0900, InKi Dae wrote: >> Thank you for your comments. >> >> it is a good idea that lcd driver registers interfaces to lcd class >> and backlight class. >> but I think for AMOLED LCD Panel, backlight couldn't be real device so >> power on/off >> for backlight device doesn't make sense. > > The backlight power control can just turn the backlight level down to > its lowest setting (off)? >> I had tried lcd driver registers interfaces to lcd class and backlight >> class as you said. >> and also backlight fake driver as Pavel said. > > So you've tried this, what was the problem? Perhaps post this driver > code to illustrate your problem? all the cases worked fine. it's not whether lcd driver has a problem or not. I mean it's design issue of lcd class. AMOLED LCD Panel DOESN'T NEED backlight device. and I should have added brightness control feature to AMOLED LCD Panel driver not using backlight class because they have no BACKLIGHT DEVICE. in point of view AMOLED LCD Panel, brightness control is perfomed by gamma setting, not backlight power controlling. -- 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: Richard Purdie on 11 Nov 2009 04:40 On Wed, 2009-11-11 at 15:17 +0900, InKi Dae wrote: > 2009/11/10 Richard Purdie <rpurdie(a)linux.intel.com>: > > So you've tried this, what was the problem? Perhaps post this driver > > code to illustrate your problem? > > all the cases worked fine. > it's not whether lcd driver has a problem or not. > I mean it's design issue of lcd class. AMOLED LCD Panel DOESN'T NEED > backlight device. > and I should have added brightness control feature to AMOLED LCD Panel > driver not using backlight class > because they have no BACKLIGHT DEVICE. > > in point of view AMOLED LCD Panel, brightness control is perfomed by > gamma setting, not backlight power controlling. The question is whether this gamma control does the same thing as what we've traditionally used the backlight brightness control for. As I understand it, the answer is yes and to userspace making it appear as a backlight brightness control makes sense. The userspace view of the world is key and the fact there is not a traditional physical backlight in the hardware isn't really an issue. Why would we want to create two userspace interfaces doing the same thing which would mean we just have to complicate userspace drivers? Symlinking just makes things confusing. Cheers, Richard -- 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 12 Nov 2009 22:20 Ok, I understood your answer. Just it was my idea for AMOLED LCD Panel. Both of them (AMOLED, TFT-LCD) do same thing in terms of brightness control as you said. Thank you, Richard. Best Regards, InKi Dae. 2009/11/11 Richard Purdie <rpurdie(a)linux.intel.com>: > On Wed, 2009-11-11 at 15:17 +0900, InKi Dae wrote: >> 2009/11/10 Richard Purdie <rpurdie(a)linux.intel.com>: >> > So you've tried this, what was the problem? Perhaps post this driver >> > code to illustrate your problem? >> >> all the cases worked fine. >> it's not whether lcd driver has a problem or not. >> I mean it's design issue of lcd class. AMOLED LCD Panel DOESN'T NEED >> backlight device. >> and I should have added brightness control feature to AMOLED LCD Panel >> driver not using backlight class >> because they have no BACKLIGHT DEVICE. >> >> in point of view AMOLED LCD Panel, brightness control is perfomed by >> gamma setting, not backlight power controlling. > > The question is whether this gamma control does the same thing as what > we've traditionally used the backlight brightness control for. As I > understand it, the answer is yes and to userspace making it appear as a > backlight brightness control makes sense. > > The userspace view of the world is key and the fact there is not a > traditional physical backlight in the hardware isn't really an issue. > > Why would we want to create two userspace interfaces doing the same > thing which would mean we just have to complicate userspace drivers? > Symlinking just makes things confusing. > > Cheers, > > Richard > > > -- 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/
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