Linux problems with Acer A315-42-R296 and parameter AMD-IOMMU

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I have detected a problem in different versions of Linux (Ubuntu 20.04, ...) with Acer A315-42-R296 when AMD-IOMMU BIOS parameter is enabled

Problem detected

The graphical environment does not work correctly when laptop is started without the power charger connected and the parameter AMD-IOMMU is enabled.

If the laptop is connected to the power charger, the error does not occur

<div>&nbsp; &nbsp; BIOS Information:</div><div>	&nbsp; &nbsp; Vendor: Insyde Corp.</div><div>	&nbsp; &nbsp; Version: V1.07</div><div>	&nbsp; &nbsp; Release Date: 12/04/2019</div>

<div>&nbsp; &nbsp; DMESG Information:</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.072235] AMD-Vi: ivrs, add hid:PNPD0040, uid:, rdevid:152</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.667395] pci 0000:00:00.2: AMD-Vi: Unable to read/write to IOMMU perf counter.</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.670728] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.670729] pci 0000:00:00.2: AMD-Vi: Extended features (0x4f77ef22294ada):</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.670731] AMD-Vi: Interrupt remapping enabled</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.670731] AMD-Vi: Virtual APIC enabled</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.670893] AMD-Vi: Lazy IO/TLB flushing enabled</div><div>&nbsp; &nbsp; &nbsp; &nbsp; [&nbsp; &nbsp; 0.918395] AMD-Vi: AMD IOMMUv2 driver by Joerg Roedel <jroedel@suse.de></div>

<div>&nbsp; &nbsp; Kernel Information:</div>&nbsp; &nbsp; &nbsp; &nbsp; 5.4.0-37-generic

Solutions:

     Solution 1: BIOS & Advanced & AMD-IOMMU set as Disabled

     Solution 2:

                        Step 1. Disable IOMMU in /etc/default/grub with amd_iommu parameter

                                            GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amd_iommu=off"

                        Step 2. update-grub    

Someone has better solutions?
 

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Acer-Samuel

DIGITALIZAAAPP

I have found the problem, it is in Kernel 5.4 and AMD

In Kernel 5.5 there is major rework to AMD IOMMU driver 

    http://lkml.iu.edu/hypermail/linux/kernel/1911.3/04736.html

and the problem has been solved.

Solutions:

- Kernel 5.4 used by default in Ubuntu 20.04, Xubuntu 20.04, etc. (proposed solutions in the first message):

 

     Solution 1: BIOS & Advanced & AMD-IOMMU set as Disabled

     Solution 2:

                 Step 1. Disable IOMMU in /etc/default/grub with amd_iommu parameter

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amd_iommu=off"

                 Step 2. update-grub    

- Kernel 5.6 (Upgrade Kernel branch)

  

    Step 1. Get latest kernel from https://kernel.ubuntu.com/~kernel-ppa/mainline

                    Today (06/28/2020 latest kernel version for 5.6 is v5.6.19)

    Step 2. Download deb files for install kernel 

<div>cd /tmp/
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.6.19/amd64/linux-headers-5.6.19-050619_5.6.19-050619.202006171132_all.de
</div><div>wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.6.19/amd64/linux-image-unsigned-5.6.19-050619-generic_5.6.19-050619.202006171132_amd64.deb
</div><div>wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.6.19/amd64/linux-modules-5.6.19-050619-generic_5.6.19-050619.202006171132_amd64.deb</div>

    Step 3. Install kernel packages

sudo dpkg -i *.deb

    Step 4. Reboot Linux and check Kernel version

uname -a

Command result: Linux Laptop 5.6.19-050619-generic #202006171132 SMP Wed Jun 17 16:31:10 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

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