Defaulting Radeon GCN 1.0/1.1 GPUs To Better Linux Driver Is Held Up By Analog Outputs

[tuxayo]

It's incredible how AMD always come with funny reasons about why it is better to keep GCN 1.0/1.1 on radeon.

It doesn't look a funny reason. It's about tolerating or not an update that has benefits but has the tradeoff of causing a black screen on existing analog setups.[1] Or are you referring to something else?

[1] Like mine. (DVI => VGA adapter since years even if not using a GCN CPU) I not even sure I would have found out it would be due to analog output if switching to AMDGPU gave me a black screen. I would 1st though about the fact that it's experimental support and that's all.

After doing a lot of install parties with people that are very representative of in terms of skills to a sample taken out of the street, it's reassuring to know that these kind of choices are considered with a lot a caution by the driver devs.

[YamashitaRen]

Black screen only happens when DC is enabled.

https://lists.freedesktop.org/archives/amd-gfx/2020-August/052332.html

Nobody asked them to enable DC by default. Just to make amdgpu the default driver for all of GCN, which they are refusing to do for years while it works perfectly fine and is arguably a better and more featured driver than radeon.

[agd5f]

Black screen only happens when DC is enabled.

https://lists.freedesktop.org/archives/amd-gfx/2020-August/052332.html

Nobody asked them to enable DC by default. Just to make amdgpu the default driver for all of GCN, which they are refusing to do for years while it works perfectly fine and is arguably a better and more featured driver than radeon.

It's not just analog encoders. amdgpu is also missing VCE support (video encoding) for SI, and display audio is also problematic on amdgpu compared to radeon without DC. There are probably also lots of other small subtle differences between the two drivers that could affect various configurations in the wild. It really comes down to deciding whether the upsides outweigh the downsides for the user/distro/developer.

[caligula]

if those adapters are passive, they require either analog output from card or digital input from monitor

I don't think HDMI pins carry any analog signal.

[tuxd3v]

yes you are fully right we do not talk about "Quality" product... but on the other hand 1-2€ is not a big problem to replace it.

If it is a necessity, we should have to live with the limitation..
At same time we should prepare ourselves to buy adapters not per unity, but per Kilogram, since they are not very good quality.. we will need a lot of them

[chithanh]

I don't think HDMI pins carry any analog signal.

Normal ones don't, but in some laptops there are special implementations where the HDMI port can output an analog VGA signal using a very cheap passive adapter.

[tuxayo]

Black screen only happens when DC is enabled.

https://lists.freedesktop.org/archives/amd-gfx/2020-August/052332.html

Nobody asked them to enable DC by default. Just to make amdgpu the default driver for all of GCN, which they are refusing to do for years while it works perfectly fine and is arguably a better and more featured driver than radeon.

Ok it's only when enabling DC! I didn't know what was that thing. (Display Core)

Thanks for the info, it looks much less of an issue now.