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Enabling AMD Radeon FreeSync On Linux 5.0

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  • #31
    Originally posted by Masush5 View Post
    What good would freesync actually do for a desktop compositor? They can just sync with the monitors max refresh rate (aka vsync), no need for variable refresh rate.
    syncing at 60 hz does not work well for 24 fps movie. you show each movie frame either 2 or 3 monitor frames

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    • #32
      Freesync not only injects frames or prevents tearing, it smooths out apparent on screen performance, syncing frames better. If you have a game where fps jumps around like a mad squirrel (many) then it certainly is beneficial.

      Sadly Linux isn't up to windows level of VRR support, not going to take a interest in it under Linux until someone fixes it up.
      Last edited by theriddick; 03-04-2019, 11:27 PM.

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      • #33
        Originally posted by atomsymbol View Post
        In case you (or somebody on this forum) own a 144Hz monitor:
        i own 240 hz monitor, but i didn't test fs, fedora uses modesetting ddx by default and i feel lazy
        Originally posted by atomsymbol View Post
        Is FreeSync of 40-144Hz beneficial over plain 144Hz refresh rate?
        yes. if your game needs 1/60 of second to generate frame, it will use 3 frames of monitor, i.e. 1/48 of second, i.e. worse than plain 60 hz monitor. freesync can give it 1/60 of second.
        Originally posted by atomsymbol View Post
        Does FreeSync result in less stuttering compared to plain 144Hz assuming the game is rendering frames at 40-80 FPS?
        if there are no bugs in implementation (there was one fixed recently)

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        • #34
          Originally posted by xxmitsu View Post
          My HP Envy x360 15-cp0001na with AU Optronics AUO22ED panel, was recognized as FreeSync capable 40 - 60 Hz on windows. But not on linux with kernel 5.0
          xrandr --prop says vrr_capable: 0

          Maybe I need to manually edit EDID data or something..
          A post in the previous FreeSync thread noted similar issues on an Acer Nitro 5 (works on Windows, doesn't work on Linux). In the end, the EDID had to be modified.

          https://www.phoronix.com/forums/foru...97#post1079597

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          • #35
            Originally posted by atomsymbol View Post

            In case you (or somebody on this forum) own a 144Hz monitor: Is FreeSync of 40-144Hz beneficial over plain 144Hz refresh rate? Does FreeSync result in less stuttering compared to plain 144Hz assuming the game is rendering frames at 40-80 FPS?
            No.
            Vsync has two disadvantages over freesync: in case source can't catch display's refresh rate vsync adds additional lag, which is lesser than monitor's frame time and in that case it limits fps to half of monitor's refresh. In case of 144hz both these disadvantages are unnoticeable, you won't see less than 7ms lag and won't suffer from limiting fps to 72hz.
            But there is one disadvantage of freesync over vsync: most of freesync monitors don't support adaptive overdrive. As you may know, all LCD matrices are slow like hell, especially when switching from gray to gray. To fix this, all monitors are using overdrive, instead of setting desired brightness of subpixel they set more contrast one, which results faster switching and masks slowness (half of frame time pixel is darker than desired and half of frame time is brighter). But this trick works well only when frame time is known. When using variable refresh rate monitor should adapt overdriving coefs to actual frame time. All gsync monitors have adaptive overdrive feature, nvidia requires this. For AMD this is optional.
            Last edited by Khrundel; 03-05-2019, 03:00 AM. Reason: fixed typos

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            • #36
              Your statement is completely wrong. The lag difference between 7 and 14ms is very noticeable otherwise 144 Hz panels wouldn't have a right to exist. But they do.
              Also, it's not 72 FPS, it will do hard jumps between 144, 72, 48, 36... FPS. The frame time graph will look like a step function with multiples of ~7ms which is the complete opposite of smoothness.

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              • #37
                Originally posted by juno View Post
                Your statement is completely wrong. The lag difference between 7 and 14ms is very noticeable otherwise 144 Hz panels wouldn't have a right to exist. But they do.
                Also, it's not 72 FPS, it will do hard jumps between 144, 72, 48, 36... FPS. The frame time graph will look like a step function with multiples of ~7ms which is the complete opposite of smoothness.
                Facepalm
                Due to matrices overdrive each monitor must have input lag at least for 1 frame period. Most have more than one, especially TVs withtout game mode activated. Up to 50ms for nongaming displays. So, even with best monitor you will see 1 frame after videocard passed it to the monitor. 10-15 milliseconds. But, before it will pass frame videocard have to render it. With 60 fps, rendering takes about 15 ms. So, you will see frame 30ms after videocard have started to render it. But before videocard will start to render it, gpu driver have to pass command buffer to it and command buffer may contain several frames (up to 3 with direct3d), so it is safe to assume opengl/vulkan usermode driver have to process rendering commands 50-60ms before you will see frame. Modern cpu-bound rendering engines must feed commands to opengl and it takes even more time, lets assume 3-5 ms. And before starting to render game should compute world change, usually it recomputes 1/60 seconds, so another 15ms. 70-80ms. And, at last, you have to add lag of mouse and lag of OS input processing. So, you see image moving at least 100 milliseconds after you've moved the mouse. Additional 3.5-7ms of 144hz vsync lag will surely ruin everything.
                Text about fps jumping is same garbage. All these jumps with 120+ monitors are far beyond human ability to notice.

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                • #38
                  Also note that Vulkan games are not supported at this time for FreeSync by RADV or AMDVLK drivers.
                  Michael Do you have any information about when FreeSync will be supported by RADV ?

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                  • #39
                    Originally posted by elovin View Post
                    Is there any information available about when FreeSync will be supported by RADV ?
                    No, freesync is easy to implement for amdgpu and radv developers, but AMD has zero interest because they have AMDVLK and it will have freesync more probably than radv.

                    Originally posted by elovin View Post
                    Is LFC (low frequency compensation) also supported ?

                    No and I see no use for that. All my Linux games works in the freesync range 40-60Hz and faster, graphics setting maximized at 4 K with RX570. Games that work with freesync:
                    Rocket League, Euro Truck Simulator 2 Demo, Project: Gordon Demo, War Thunder, Sanctum 2 , Tomb Raider 2013 , Saints Row 2

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                    • #40
                      Originally posted by Khrundel View Post
                      Facepalm
                      LOL

                      Stop spreading nonsense. Every healthy human is able to notice the difference in frame time smoothness comparing 7 ms, 14 ms, 21 ms, 21 ms, 28 ms, 7 ms, 21 ms, ... to 7 ms, 7 ms, 7 ms... or even 28 ms, 28 ms, 28 ms... If you aren't, I would rather have my eyesight checked - or my bias. Some find it more disruptive, others less. But the latter group can still notice the difference if it is pointed out by someone.

                      I don't even care to elaborate on the rest of your wrong and even contradictory statements as long as you play the ignorant prime example of dunning-kruger.
                      Last edited by juno; 03-05-2019, 09:12 AM.

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