Notebooks Reasons *not* to buy an XPS 13?

I've been having some problems with the wireless on this thing, even after replacing the Killer thing with a proper Intel jobby: dropping off the 5GHz band, refusing to transfer packets for a bit, and occasionally even just refusing to authenticate until I reboot the thing. S'one of those things where you don't know whether to blame the laptop or the router, and it does seem to be better when I'm not in the congested part of the 5GHz spectrum - but, sadly, Netgear's radar detection is a little over sensitive and it keeps throwing itself off clear and free Channel 112 and back to noisy ol' Channel 36.

So, I've gone for the nuclear option: iwlwifi backports, compiled from source and with the latest firmware (-31 instead of -21 from Ubuntu's 16.04.3 repos and -22 direct from Intel.) Only time will tell if it's fixed the problem, though, but I can say that it has made iwconfig think the Wi-Fi card has no wireless extensions available...

 

Well, the problem with the Killer card was different: that wasn't allowing traffic on 5GHz at all, ever.

2.4GHz is usually better, but sometimes has the same trouble. I'm now typing from a rock-solid 5GHz connection which is happily maxing out my 60Mb/s broadband line, but only after moving the channel on the router back into the hundreds - before doing that I was getting 25Mb/s at best.

It's a puzzler, this one!

 

It *may* - or may not, who knows - be a regulatory domain issue.

Code:

blacklaw@xerxes:~$ iw reg get
country 00: DFS-UNSET
   (2402 - 2472 @ 40), (6, 20), (N/A)
   (2457 - 2482 @ 20), (6, 20), (N/A), PASSIVE-SCAN
   (2474 - 2494 @ 20), (6, 20), (N/A), NO-OFDM, PASSIVE-SCAN
   (5170 - 5250 @ 80), (6, 20), (N/A), PASSIVE-SCAN
   (5250 - 5330 @ 80), (6, 20), (0 ms), DFS, PASSIVE-SCAN
   (5490 - 5730 @ 160), (6, 20), (0 ms), DFS, PASSIVE-SCAN
   (5735 - 5835 @ 80), (6, 20), (N/A), PASSIVE-SCAN
   (57240 - 63720 @ 2160), (N/A, 0), (N/A)

That ain't right, is it? Quick switch of the card into managed mode and I can fix that...

Code:

root@xerxes:~# modprobe -r iwlwifi && modprobe iwlwifi lar_disable=1
root@xerxes:~# iw reg set GB
root@xerxes:~# iw reg get
country 98: DFS-ETSI
   (2402 - 2482 @ 40), (N/A, 20), (N/A)
   (5170 - 5250 @ 80), (N/A, 20), (N/A), NO-OUTDOOR
   (5250 - 5330 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS
   (5490 - 5710 @ 160), (N/A, 26), (0 ms), DFS
   (57000 - 66000 @ 2160), (N/A, 40), (N/A)

It still ain't quite right, as it's claiming country code 98 instead of GB like wot I told it to be - but that might be a side effect of the fact my stupid Netgear router doesn't ask for a country-based regulatory domain but a region-based one, and when you choose 'Europe' it helpfully broadcasts a country code of DE...

Still, GB, DE, and 98 should all be identical in terms of what they are and aren't allowed to do radio-wise, so fingers crossed this has finally fixed the glitch!

EDIT: Y'see, when it works it's perfectly happy...

 

Ooh, now I've got a new thing to add to the list of annoyances: I may have tweaked the power a little too much, because it's now aggressively downclocking to about 450MHz while I'm trying to watch something on Amazon Instant Video - which ain't enough to keep the video stream fed and causes it to glitch.

<sigh>

EDIT: Easily and quickly fixed with a switch to the performance CPU governor, though - with an obvious impact on battery life, mind!

 

Sometimes I think life would be so much easier if I just bought a Windows laptop and didn't fiddle. But where's the fun in that!

I can get stable video if I set a minimum clockspeed of 700MHz through cpupower, which strangely allows it to downclock to around 600MHz - which is good enough to keep Amazon Instant Video from glitching, though going in and out of full screen takes a couple of seconds each time. Still idling at sub-3.5W, currently at 3.97W as I type this and an alert pops up above the text entry box - so I'm happy enough with that.

Seems to be solved with a minimum real-world CPU clock of 600MHz, as far as I can see - although I'm happy to try other tricks if you think it'll work better!

EDIT: Switching to the performance governor idles at around 4.14W, so frankly unless I'm absolutely gasping for as much battery life as possible I might just leave it there by default.

EDIT EDIT: Idle might be similar, but watching Amazon Video on the performance governor sits at about 12-16W, whereas doing the same on the powersave governor with a 750MHz minimum clock (figured I'd add a little wiggle-room) is 6-7.5W - so powersave with a manual lower limit it's going to be!

 

S'dead easy: you just write the number you want in megahertz to /sys/class/drm/card0/gt_min_freq_mhz (or gt_max_freq_mhz to set an upper limit), then you can read back the current speed at any given time by catting /sys/class/drm/card0/gt_cur_freq_mhz.

Can't say that a minor boost to that does much, though, especially compared with the CPU tweak. It was certainly worth a shot - ta for suggesting it!

 

Bwa-ha-haaa!


That's not even idle, I'm SSH'd into my server to chat on IRC and actively using my web browser - *and* I've still got the 750MHz minimum clock enforced. I've been using it off and on this evening, too. Crazy stuff!

 

Dunno, but as it doesn't have an Ethernet port and I'd have to use a USB dongle I'm guessing wired might actually take a smidge more power than wireless.

 

I think the XPS 15 might, but not the 13 - just two USB 3.0 ports, a USB 3.1/Thunderbolt Type-C, 3.5mm jack, and SD card slot. Plus some weird locking slot that I think was cheaper for Dell to license than a Kensington slot but no bugger sells a lock for.

Aye, it's pretty hefty - takes up about half the chassis, far as I could see as I was changing the Wi-Fi card!

 

It actually is! I mean, not field-removable like the Inspiron I had back in the 90s, but you just pop the back cover off (about seven or eight T5 screws and a Philips) and the battery's right there. Unscrew it, unclip it, swap it over, clip it, screw it, put the back cover and screws back and job's a good 'un. There's an iFixit guide 'ere with pretty pichures.