[RndTbl] recommendations for 4k video card under Linux

[Adam Thompson]

(Top-posting to save time, sorry)

You need HDMI 2.1 for guaranteed 5k support.  IIRC, HDMI 2.0 guaranteed 
4k support.
When I say "guaranteed", I don't mean "HDMI Assoc. says it'll work", I 
mean "yes, it's going to work in the real world".

Hanging a non-passthrough DP monitor off of a passthrough-capable 
monitor is exactly the use case that feature is designed for.

I sincerely hope that TB3 takes over as a video cabling standard and 
finally replaces both DP and HDMI, but I don't really think it'll 
happen...  in any case a single 40GBps TB3 connection still only 
supports 1 x 5k or 2 x 4k displays.

-Adam


On 2018-04-07 01:19, Trevor Cordes wrote:
> On 2018-04-06 Gilles Detillieux wrote:
>> Hi. Does anyone on the list have experience and recommendations on
>> how to support a 4k monitor under Linux? We want to use a single Dell
> 
> Hi, I mentioned at a MUUG meeting roundtable last year that I had
> picked up a "2k" (2560x1440) monitor and card and got it working.  All
> my research and picks apply to 4k also, so my results might be useful 
> to
> you.
> 
> First off, you want DP.  2k is hard with HDMI, and 4k is doubly so.
> Many cards (especially cheaper/older ones) may claim to do high rez's
> but their HDMI out port won't, as it's not a new enough spec.  From
> memory, you need something like 1.6 instead of 1.4 or whatever (can 
> find
> online) but good luck finding out precisely what the HDMI port on your
> card actually is from the Taiwan Inc websites.
> 
> Same thing applies to cables, for 4k you'll probably need a newest-gen
> cable, and they are equally as hard to deduce precisely what version
> they are!  DP doesn't suffer from this problem on either front.  If you
> get a DP card that says it does 4k, it does 4k, guaranteed, and the
> cables are basically all 4k supporting unless you find something really
> old.
> 
> I tried about 4 different combos of card and 2k monitor before finally
> getting something to work, so I'm pretty sure I've figured out the
> cheapest (nvidia) way.  And when things aren't going to work, they just
> don't work.  You're just stuck at the lower rez with no option to go
> higher and no hint as to why.  I suppose you could probably get things
> working at lower clocks using xorg.conf modelines like the bad 'ol
> days, but I didn't want to delve there.  When you get the right parts
> it all "just works".
> 
> The cheapest card that I could find that would support 4k and DP and
> vdpau (important for me) was the GTX 1050.  Any 1050 with DP out should
> be A-OK.  I sell them for just over $200, but I'm sure there are deals
> elsewhere out there.
> 
> I'm not 100% positive but I think when I first booted up with my
> nouveau drivers they didn't work and it fell back to fb or vesa or
> something.  That was 1 year ago.  Eventually nouveau will support the
> 1050, maybe already does.  The chipset codename according to lspci is
> GP107 if that helps.
> 
> No whoop, I switch between nouveau and nvidia binaries frequently when
> FLOSS support catches up with the technology.  "Updating kernel ate my
> nv binary" hasn't been a concern for me for at least 5 years now.  If
> you're using Fedora, just use the rpmfusion nvidia and (a|)kmod-nvidia
> rpms and every time you dnf update the kernel the binaries auto-compile
> and you have to do zero additional steps when you reboot.  It just
> keeps working.  (And it bypasses having to wait for the repo guys to
> update the non-akmod rpm version which always takes 1-2 weeks!)
> 
> One caveat: after the dnf update finishes, wait about 2 minutes for the
> gcc processes to finish compiling or you'll be foobar until you run
> akmod --somethingorrather from a single boot. (Nothing at all indicates
> you need to wait after an update before rebooting.)
> 
> I'm probably stuck with binaries for a long time as I really like vdpau
> now and I'm pretty sure that won't be in the FLOSS drivers for many
> more years, if ever.  The binaries are pretty good.  No stability
> issues, though sometimes there's little cosmetic glitch bugs that they
> eventually hammer out in updates (I currently have zero of these
> occurring).  The only sucky part is if you want to bisect/debug for the
> LKML guys (which I seem to do way too often lately) you'll need to
> reproduce your bug in non-tainted before posting your results.
> 
> My monitor is also a Dell (2k) and it's great.  Their quality/price
> ratio can't be beat on mid/high-end monitors.  I sell quite a few and
> can often get amazing prices on Dell LCDs through my suppliers, so if
> you're in Wpg give me a shout.
> 
> My next project is to try the DP daisychain feature as I want 2 x 2k
> LCD instead of my current 2k + 1600x1200.  And I'm not convinced the
> 1050's HDMI will do 2k or 4k so daisychain might be the only option.
> (My big q is can a non-daisy LCD daisy off a has-daisy LCD or do both
> need to be daisy-capable, i.e. with passthru.)  If a 2nd 2k/4k monitor
> is in your future give the daisy port yes/no feature serious
> consideration before you buy your first one.  No "affordable" card I
> looked at had dual DP out.
> 
> I'll end with a quick note about 2k vs 4k.  I thought long and hard
> about which to buy, as the price diff was sub-$200.  I went with 2k as
> I do almost zero graphics/images and I realized that for my workload,
> normal daily desktop use + 90% cmd line and programming work, 4k would
> buy me nothing.  In fact, besides graphics work I can't see any use for
> 4k.  My goal is always the most usable real estate, and with 2k on a
> 24" I was able to vastly increase my pixel count yet keep all my
> working terminal font sizes constant at 9 pixel mono terminal font.
> 
> I guess what I'm saying (and I'm sure you've already thought about it)
> is don't just say "ooooh 4k" and get that, think about what you are
> really trying to achieve.  The other upshot of picking 2k, besides
> price, is that you can go 2 x 2k fairly easily on most cards, but 2 x
> 4k might go beyond the $200 cards' max overall screen dimensions.
> 
> Good luck!  And if you ever daisychain, let me know.
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