Home / ubuntu / Questions / 1255232
In Process
MagusZ
Asked: 2020-07-01 16:14:39 +0800 CST

Ubuntu 20.04 on a new Lenovo IdeaPad Flex 5 is not detecting my second monitor through HDMI

  • 772

As the title states I recently purchased an 81X2 IdeaPad Flex 5 14ARE05 with an AMD Ryzen 7 4700U with Radeon Graphics (8) @ 2.000GHz for the CPU and an AMD ATI 04:00.0 Renoir for the GPU. I installed Ubuntu 20.04 and chose to install 3rd party proprietary drivers etc.. I then tried to connect it to an external monitor through HDMI and it did not work. The monitor and HDMI cable are fine, I just used them yesterday and they worked just fine. What information do I need to diagnose the problem, and then how do I fix it? Apologies for not posting more information, I have no idea where to start and all of the answers online were for Nvidia.

Edit: I tried installing Xubuntu without the 3rd party driver option and it still does not work. The menu for displays comes up when i connect and disconnect the HDMI so it must detect something. Regarding the actual technical info, this is what I got from lspci -i:

04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir (rev c2) (prog-if 00 [VGA controller])
    Subsystem: Lenovo Renoir
    Flags: bus master, fast devsel, latency 0, IRQ 255
    Memory at 460000000 (64-bit, prefetchable) [size=256M]
    Memory at 470000000 (64-bit, prefetchable) [size=2M]
    I/O ports at 1000 [disabled] [size=256]
    Memory at fc500000 (32-bit, non-prefetchable) [size=512K]
    Capabilities: <access denied>
    Kernel modules: amdgpu
multiple-monitors hdmi amd-graphics 20.04 amd-ryzen

1 Answers

  1. What I found is that Ubuntu 20.04 is shipping with Linux kernel version 5.4 and it looks like the support for the AMD Ryzen chip didn't get added into the default build of the kernel until version 5.7.

    See this article on ubuntuhandbook.org for a bullet description of what's in 5.7 and a description of how to install it on Ubuntu 20.04:

    • Download the kernel files from this download page

      Most users will want the generic kernel image. You will need to download four files

      • linux-headers... (generic or low-latency)
      • linux-headers......all....
      • linux-image... (generic or low-latency)
      • linux-modules... (generic or low-latency)

    • After downloading, you can install these .deb files using Gdebi or whatever graphical installer your system suggests opening them with, or using the dpkg command in the directory where you downloaded the files:

      sudo dpkg -i filename.deb

      Where filename is the name of the file to install (start typing the filename e.g. linux-headers and press tab to get the full name to appear).

    Also note that the downloaded kernels aren't signed so I needed to turn off UEFI security (also known as "secure boot") to load this new kernel. Preferably you can sign your copy of the kernel.

    • 4