On Fri, Nov 20, 2015 at 04:46:07PM -0700, Azael Avalos wrote: > Hi Darren, > > 2015-11-20 16:16 GMT-07:00 Darren Hart <dvhart@xxxxxxxxxxxxx>: > > On Sun, Nov 15, 2015 at 08:32:47PM -0700, Azael Avalos wrote: > >> If transflective backlight is supported and the brightness is zero > >> (lowest brightness level), the set_lcd_brightness function will activate > >> the transflective backlight, making the LCD appear to be turned off. > >> > >> This patch fixes the issue by incrementing the brightness level, and > >> by doing so, avoiding the activation of the tranflective backlight. > > > > So... I'm not sure this is a bug or even wrong behavior. The lowest setting on > > my Thinkpad Yoga 12 is also "off" in Linux. Same is true for my Mac Book Pro (in > > Mac OS X). > > Yeah, and even on "regular" (with non transflective backlight) Toshibas > zero is also "off" and no problem is observed. > > > > > From what I can tell, what this patch does is merely disable the lowest setting. > > Nope, we are just not letting the driver enable transflective backlight > and continue using the "normal" brightness range. > > > > > What is it about this behavior that is considered to be wrong? > > > > The problem is with laptops with transflective backlight support. > > The code for transflective backlight is fused with the LCD backlight > code (go figure...), so if a Toshiba laptop with transflective support > is detected, the max brightness levels are raised by one. > > A regular laptop's brightness levels are 0-7, but on a laptop with > transflective support, the brightness levels are 0-8, zero being > "activate transflective backlight" and 1-8 the regular brightness > levels. > > So, when a laptop with transflective support AND an initial > brightness level of zero gets probed for backlight support, > the set_lcd_brightness function activates the transfective > backlight, as the brightness levels are still not incremented, > and thus, the screen goes dark. > > > I hope this clarifies a bit the situation here. Thanks, queued to testing. -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
