Re: amdgpu does not support 3840x2160@30Hz on kaveri apu

Davide Corrado <davide@xxxxxxxxxxxxxxxx> · Mon, 4 Jan 2021 13:37:45 +0100

Btw, should the driver switch to the lower supported resolution then?

Il Lun 4 Gen 2021, 13:04 Davide Corrado <davide@xxxxxxxxxxxxxxxx> ha scritto:
Hello. This resolution is supported by the Apu and the motherboard specs. Will try what you suggest and let you know

Il Lun 4 Gen 2021, 12:10 Christian König <ckoenig.leichtzumerken@xxxxxxxxx> ha scritto:

    Hi Davide,

      adding a few of our AMD display people.

      In general as already suggested by others opening a bug report to
      track this is the right thing to do.

      In the past we had a few bug reports like this because amdgpu is
      more strict in checking hardware limitations.

      For example it can be that your HDMI port on the board can only
      handle a certain maximum pixel clock, but radeon is ignoring this
      while amdgpu isn't.

      What you can try to do is to manually override the used mode, e.g.
      copy the modeline used when radeon is active and manually add that
      using xrandr when amdgpu is active and see if it works or not.

      Regards,

      Christian.

      Am 02.01.21 um 19:50 schrieb Davide Corrado:

        hello, I'd like to report this issue that I am having since
          I updated my display (samsung U28E590). The amdgpu does not
          support the native resolution of my new monitor, which is
          3840x2160. Using a HDMI or DVI connection (I tried
          both, same results), the maximum supported refresh is 30Hz, so
          I'm stuck with that (don't have a displayport). The radeon
          module works fine, I'm having this issue just when I use
          amdgpu (which I'd like to, because performance is better).

        Some info of my hardware:

        cpu: AMD A10-7870K Radeon R7, 12 Compute Cores 4C+8G
        kernel version (I tried different ones and different linux
          distros, same results!): 5.9.16-200.fc33.x86_64 #1 SMP Mon Dec
          21 14:08:22 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
        Monitor: Samsung U28E590.

        description:

        If I boot the system using amdgpu and no video mode
          selection, the system boots but I don't get a screen during
          boot and in wayland. I can connect using ssh, so the system is
          running fine, just no display; If I force a full HD resolution
          with "video:" in the kernel line, I can see the boot process
          but the screen disappears when wayland starts (because the
          default resolution is 3840x2160@30Hz). Using a full HD monitor
          results in no issues, so it must be related to this very 4k
          resolution.

        As I have already stated, radeon module works with the same
          software/hardware configuration.

        thanks you so much for your time :-)

            -- 

                          Davide Corrado

                            UNIX Team Leader

                            Via Abramo Lincoln, 25

                            20129 Milano

                            Tel +39 3474259950

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