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. Cheers Azael -- -- El mundo apesta y vosotros apestais tambien -- -- 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