Re: Unfinished unichrome driver

[maya%NetBSD.org@localhost]

On Wed, Jul 15, 2020 at 09:18:09PM +0300, Andrius V wrote:
> Hi,
> 
> Since my VIA based hardware wasn't attaching a unichrome driver, I decided
> to take a look at it. After investigation, I found out that the driver had
> been mainly unfinished:
> * It matches only one unichrome graphics ID from (CN700 and related
> chipsets) and have some hard coded values referencing it here and there
> (also, erratically driver refers to graphics from non existent CN900
> chipset in few places, including pcidevs, likely CN700 was meant).
> * The code itself has definitions for some other unichrome graphics from
> CN400, CLE266 (and related) chipsets but not the newer ones
> (VX800/VX855/VX900).
> * Not included in amd64 ports, similarly to some other VIA specific
> hardware drivers.
> * It is mentioned in amd64 ALL configuration but without wsdisplay* at
> unichromefb?. Likely leftover from i386 and should be removed for now, same
> as viadrmums (which causes system to crash in amd64, at least on VX800/900).
> * Driver was made compatible with the legacy viadrm driver but it doesn't
> seem to work with viadrmums. My system crashed spectacularly once both
> enabled.
> 
> It successfully attached and booted with higher resolution for me on CN400
> unichrome graphics, once I added its ID without any other modifications.
> So, I believe, adding support for all unichrome drivers should not be too
> hard. Not sure why it was abandoned and what was unfinished though.
> 
> So out of that I am planning to create PRs unless someone can look at those:
> * Add support for all unichrome graphics (possibly can take a look at
> this)...
> * Make it compatible with viadrmums as it was with viadrm, if that possible.
> 
> Besides that I believe tha viadrmums and unichromefb should be removed from
> amd64 ALL kernel configuration, at least for now. And CN900 should be
> renamed to CN700 in all places.
> 
> Regards,
> Andrius V

There's someone working on drm*kms* drivers for VIA graphics hardware
for Linux, and also the X driver. It's a good direction to look for
anyone that is interested.