[Epic 4G Q&A, Help & Troubleshooting] drunix:
Just going to throw this out there since people keep chiming in with "if you understood the bug this wouldn't fix it" and others chime in with the "this is THE gps fix, it fixes everything!".

There isn't *one* GPS bug... there are several. There's a large number of people who have had GPS issues from the beginning with a stock phone... and others that have had no problems with stock. Most of the early discussion revolved around it taking a VERY long time to lock, or a very long time to lock on subsequent attempts. The "fixes" for this have been updated modems, modifying the gps.conf file for AGPS settings, replacing the time sync server in gps.conf, twiddling with wifi location settings, etc. I can't speak to the effectiveness of any of these because I've never had this problem, my GPS just straight up worked on stock.

The *second* problem I've seen talked about is the one I have. I didn't have any trouble until I flashed the DK17 modem. But the interesting part is that I couldn't for the life of me flash the DK17 modem.bin file to PHONE, it accepts it, but I got unknown baseband. Did it several times, got the same result. Eventually I gave up and flashed the .tar to PDA instead. Got DK17, got radios working, but no gps. I don't mean slow to lock, or poor reception, I mean it never detected a satellite, ever (testing using GPS Status and GPS Tester). In apps like Google Trax, it would just stick on acquiring a lock forever, and the icon in the status bar would never switch to the locked icon, always the searching one. I tried reflashing the modem, doing additional wipes (telling people straight up that they didn't wipe before they installed a ROM is not helpful, btw, you don't know that, and if you pretend to because you see they're having a symptom, you need to take a class on correlation and causation, and you need some more real life programming experience. Even if you're right 90% of the time, you can't know it, so don't pretend to). re-installing the ROM, etc. No go, exactly the same effect every time.

I won't pretend to have been around the android scene long, but I've been programming in different languages since I was 9, and using linux and customizing and recompiling linux kernels since I was 12--that's 16 years ago, at this point. I'll probably get caught on some stupid gotchas for android development, and I'm not greatly familiar with the flashing and recovery techniques available to android, but I know my way around technology and programming. I'm with you guys when you say it doesn't make sense that reflashing a DI18 ROM, getting a lock and flashing back is going to fix your GPS issues. It seems like the old "reinstall windows" concept and that the real fix is something else that we're missing. And that may very well be the case, but for the sake of discussion here, can we at least entertain the idea that not everyone having a GPS issue is a moron for long enough that we can figure out why this actually does fix the issue?

Things I did that left me with an entirely INOPERABLE GPS:

starting with my working DI18 modem/rom: flash dk17 modem, wipe and flash a dk17 rom

GPSCLRX

gps.conf changes

re-flashing dk17 modem several times

re-wiping and re-flashing a DK17 rom several times

The steps I did that took me from a non-working GPS to a working one are as follows:

Flash a stock DI18 ROM, boot it up (noting that I'm still on DK17 modem), acquire GPS signal using google maps, verify using GPS status.

Wipe and Flash back to DK17 ROM

Restore "Data" only from previous DK17 Backup

I believe there to be a strong enough correlation to people for whom the modem.bin will not flash (though modem.tar will) and this particular GPS problem, that I believe they're in some way related.

I've also not heard of this problem happening for anyone who originally had GPS problems (I've only seen/heard of this from people whose GPS worked perfectly on DI18).

I'd be interested in taking a more statistical approach to this and finding out those details from all the people who are having the completely-dead gps on DK17, but every time a thread comes up about it, 15 people chime in calling them morons and telling them they didn't flash.

I'd also be interested in the USB issues as well, but that's a topic for another discussion (my phone strongly dislikes some EHCI USB controllers, but works fine in OHCI mode on the same controller).