On Sat, Sep 23, 2017 at 7:48 AM, Roberto C. Sánchez <robe...@debian.org> wrote:
> I had this exact same problem with Jessie on an HP ProBook 650. The bug > was in X.org and was fixed when I upgraded to Stretch. The problem, as > I recall, was that certain display hardware inverts the sense of the > intensity, so that instead of it going from 0 (dark) to max (bright) it > goes from 0 (bright) to max (dark). X.org sets the display brightness > to what it thinks is max on the log in screen to compensate for the > possibility that was turned all the way down by a previous user. > > What I found as a "workaround" was that I could log in as normal and > then by using the brightness control function keys I could increase the > display brightness after logging in. > Just confirming that apparently I had this same issue with jessie 8.4 on Dell hardware. The problem only occurred if a second monitor was connected prior to boot. Only the second monitor's brightness was dialed-up at boot, the primary (laptop) screen would be dialed down to 0 brightness. Unfortunately the login prompt was on the laptop screen. Simply dialing-up the brightness was the fix, but it took me a while to realize it. -Roberto > > -- > Roberto C. Sánchez > >
