Forward to upstream for more discussion. æ äï2011-05-13 æ 17:27 +0800ïMichael Chang æåï > Melchior, > > I tried to puzzle out the possible cause of the problem, but sorry > that no further progress to give you. I'd like to debug this issue, > also did Joey. But there's more questions in my mind, made me feel not > able to proceed any further.. :( > > 1. is_backlight_combination_mode() really returns 0x4 ..? I understand > your words, but if this is true then Joey Lee provided patch should > log out some information about changing the LPBC > > set backlight lbpc = ... > > but I didn't see any of the log output .. :( > > 2. I dig the old mailing thread .. found a post > > http://marc.info/?l=linux-kernel&m=130462815211684&w=2 > > If you rebase this patch to your currently git commit, will it fixes > all problems for you now (only vanilla kernel with this patch)? (You > replied that this patch works for you ..) Also another interesting > finding... > > > + if (!lbpc) > > + combo_mode = 0; > > Looks like the purpose of it is to NOT touch the LPBC registers if > lbpc is zero ...(since this forces is_backlight_combination_mode > return 0). This would make contradiction about the assumption that you > could change to back-light via LPBC .. (using setpci is actually > access the LPBC registers .. IMHO). > > Total a mess for me now .. Did I made anything wrong .. I know I may > lose some details. > > I'm thinking is it ok for us to discuss in IRC, the communication > would be more efficient. Would this be convenient for you ? This is up > to you. > > Have nice weekend .. :) > > Regards, > Michael Chang > > 2011/5/10 Melchior FRANZ <melchior.franz@xxxxxxxxx>: > > * Michael Chang -- Tuesday 10 May 2011: > >> Could you please try this patch and get the log ? We wonder why > >> is_backlight_combination_mode () returns false. > > > > This information was already buried in the bugzilla thread: > > > > https://bugzilla.kernel.org/show_bug.cgi?id=31522 > > "It turned out that on this machine INTEL_INFO(dev)->gen equals 4, > > and is_backlight_combination_mode() returns 0x40000000." > > > > > > But to say it again in your words: :-) > > > > [drm:is_backlight_combination_mode], BLM_COMBINATION_MODE = 1073741824 (0x40000000) > > > > 6x during boot-up, and several times later when changing the backlight > > brightness. > > > > > > This was with 8b061610dac3a3b89770c85ad63b481a47b0c38e. And now > > I have a little shocker for you (and me): because this was a > > vanilla kernel (apart from these debug messages), the screen went > > black again, like I knew it. But pressing the "brightness down" > > key turns the backlight on! I can't believe that I haven't tested > > that. I guess I've only tried "brightness up" and "display toggle". > > Those don't turn backlight on. Or maybe somethine else relevant > > meanwhile changed in the i915 drivers. (I've regularly been > > updating to HEAD.) > > > > So, the problem was just the initial state all the time? > > > > m. > > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
