[BRLTTY] Brltty sounds absence with sof-firmware driver used on Linux

[Vsevolod Popov]

10.01.2022 15:29, Dave Mielke пишет:
> The log contains the following problem:
>   [brltty] USB: claiming interface: 0
>    [brltty] USB interface in use: 0 (usbfs)
>    [brltty] possible cause: another brltty process may be accessing the same device
>    [brltty] possible cause: the device may be attached to a virtual machine running on this host
>    [brltty] USB interface claim error 16: Устройство или ресурс занято
> I think the most likely cause is the first sugestion, i.e. that another instance of brltty is already accessing the same device. This is perhaps because it's being immediately started via a udev rule as soon as you connect the device.
> I'm sorry if I've forgotten some details but I need to refresh my understanding of your problem. Is it that this (probably) udev-started instance of brltty isn't working?
I have just tried to remember the problem and reproduce it and here's 
what I found.
When I disconnect a braille display and then run brltty as root, after 
connecting the display again orca doesn't communicate with brltty.
But to be honest this all system is confusing. Maybe that's because I am 
pretty new to Linux in general and I don't really understand how brltty 
handles processes.
To fix this issue after running brltty as root user, I restart the 
system and it works again.
But there is a question I have:
Alexandr mentioned that brltty uses it's own user in Arch Linux. When 
that happens, Orca works with braille as expected.
Does it mean that there is no need to run brltty as root or regular user 
at all if it is runned and used by brltty user and works with orca 
without any issues?
Do I understand correctly that if brltty starts as it's user and braille 
display works means that it's supported?
But why are errors about the braille driver displayed when running 
brltty as root?
I am sorry for maybe strange questions but I am a bit confused how it 
all works and I would like to understand it.
Thank you.
--
regards,
Vsevolod
https://github.com/sevapopov2/