Update: Ok, problem solved--I found the page "AMD/ATI Open Source Drivers (radeon, r128, mach64)" (https://wiki.debian.org/AtiHowTo), followed the instructions there, rebooted, and voila.
I guess the package that was missing was the "firmware-linux-nonfree". I'm still curious about some of the questions here, but, well curiosity apparently killed one or more cats... Sorry for the noise! regards, Randy Kramer On Monday, August 15, 2016 08:48:04 PM rhkra...@gmail.com wrote: > Subject: I can't get 1920x1080 resolution on my monitor: How find the name > of the output for a "default" setup? (New Jessie install) > > Why does xrandr use the word "default" instead of something like VGA-0? > > What is "xrandr: Failed to get size of gamma for output default" telling > me-- is it a problem? > > Background: > > I've just made a new install of Jessie on a new machine (using an Asus M5A > 78L-M USB3 motherboard). I am using the onboard graphics and a monitor > with a resolution (well, actually an LED TV) of up to 1920x1080. I have > another computer attached to the same monitor (now via a KVM switch) and > it works fine (the other computer is running Wheezy). > > I did the install using the 64-bit AMD netinst.iso from a pendrive--that > worked "fine". (Update: I've since downloaded DVD-1 and made a new install > from there using the Advanced Graphical install method--it has made no > difference (with respect to screen resolution). > > My problem is that the new computer only detected resolutions up to > 1024x768 (see below). > > I've done a fair amount of googling (and reading and experimenting, and > will keep doing that), but I wanted to ask some questions here. > > One of the things I found were instructions on how to use cvt and xrandr to > create a modeline for 1920x1080 resolution, and then put that modeline to > use--so far I haven't been successful. > > (Aside: I have used lspci and lsmod to confirm that the appropriate AMD > driver is being used.) > > One problem is that I get a message: "xrandr: Failed to get size of gamma > for output default" every time I run xrandr. I've googled for that, and > found some pages that mention it, but none (so far) that really explained > the cause of the message or how to fix it. > > Another problem is that I don't know the name of the xrandr output device. > It shows up as "default" and I've tried that, VGA1, and VGA-0, crtc 0, > primary-- (with and without quotes) and none seem to work. > > Any suggestions? > > Here is a konsole session of one of my attempts to use cvt and xrandr to > set up a new mode (as stated above, I've also tried default, VGA1, VGA-1, > VGA-0, crtc 0, primary (with and without quotes) and none have worked. > > Notice the 2nd last line which says: "xrandr: cannot find output "primary"" > > = > rhk@s31:~$ cvt 1920 1080 > # 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz > Modeline "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 > 1120 -hsync +vsync > rhk@s31:~$ xrandr > xrandr: Failed to get size of gamma for output default > Screen 0: minimum 640 x 400, current 1024 x 768, maximum 1024 x 768 > default connected primary 1024x768+0+0 0mm x 0mm > 1024x768 0.00* > 800x600 0.00 > 640x480 0.00 > 720x400 0.00 > rhk@s31:~$ xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 > 1080 1083 1088 1120 -hsync +vsync > xrandr: Failed to get size of gamma for output default > rhk@s31:~$ xrandr > xrandr: Failed to get size of gamma for output default > Screen 0: minimum 640 x 400, current 1024 x 768, maximum 1024 x 768 > default connected primary 1024x768+0+0 0mm x 0mm > 1024x768 0.00* > 800x600 0.00 > 640x480 0.00 > 720x400 0.00 > 1920x1080_60.00 (0x1b9) 173.000MHz > h: width 1920 start 2048 end 2248 total 2576 skew 0 clock > 67.16KHz > v: height 1080 start 1083 end 1088 total 1120 clock > 59.96Hz > rhk@s31:~$ xrandr --addmode primary "1920x1080_60.00" > xrandr: Failed to get size of gamma for output default > xrandr: cannot find output "primary" > rhk@s31:~$ > =
