dougg3

6 ms·

1.
by dougg3 10mo ago
Very cool that you worked on the OMAP3 and BeagleBoard! I didn't ask anybody else about it. I just decided to tinker with my USB sniffer to try to get to the bottom of what was going on. I'm still a little puzzled about why the 2
2.
by dougg3 10mo ago
That's a really excellent point. I will do that!
3.
by dougg3 1y ago
Thank you! Hopefully it works for you. I guess I should reword the way I said something in the previous message: when I said "it can force the monitor to always be detected", I really should have said "it forces the monitor t
4.
by dougg3 1y ago
Yeah, if you are 100% confident you're using your GPU's I2C controller it's probably fine, but the reason I warned about it repeatedly in the post was because I stumbled upon this GitHub issue where two people accidentally fl
5.
by dougg3 1y ago
I also have a couple of passthroughs -- I probably should have mentioned them in the post as another option. The one I have is fancy -- it can read the EDID from a monitor, save it, and use it as an override for another monitor. Another awe
6.
by dougg3 2y ago
That’s what that was? I noticed it while looking through the Apple HD SC Setup code and assumed it had something to do with A/UX, but had no idea. Good to know!
7.
by dougg3 2y ago
Another option, if you can’t find a card, is a ZuluSCSI or BlueSCSI V2 in initiator mode to image the drive to an SD card. It’s pretty nifty! I’ve recently even been using ZuluSCSI as a USB-SCSI bridge with USB MSC initiator mode.
8.
by dougg3 2y ago
There are indeed some aluminum electrolytics hiding on Quantum drives. They look sneakily like tantalum caps, but they're just cans hiding inside a plastic cover. Here's one where I accidentally broke the cover, revealing what&#x2
9.
by dougg3 2y ago
It also appears that I may not have been the first one to discover that something odd was going on with that bit, causing it to use A0-A7 (with weird results) instead of D0-D7: https://eab.abime.net/showthread.php?t=119675
10.
by dougg3 2y ago
Don't you think, as a Mac ROM developer, the chances of your software bug being accidentally fixed by the CPU through an undocumented instruction are pretty low? That's what I was getting at when I wrote that. Of course they would
11.
by dougg3 2y ago
I’ve been trying it out a bunch lately. From what I’ve seen, machines with Egret don’t have it enabled by default, but machines with the newer Cuda do.
12.
by dougg3 2y ago
My test of an 040 (no A1 change, D1 changed) was on a chip with the following markings: XC68LC040RC25B 02E23G QEDP9348D MALAYSIA
13.
by dougg3 2y ago
Thank you! Yes, I will definitely make another post if and when someone figures out what the instruction does.
14.
by dougg3 2y ago
On the 040, it seems to do something that actually involves D1. Definitely doesn't touch A1 at all. I didn't test further, but it's possible it just handles the instruction as a normal CAS. It did cause a system error the fir
15.
by dougg3 2y ago
Author here. Yeah, I have a tendency to go into pretty big deep dives when I find stuff like this. It's so rewarding at the end, even if it does take a lot of time!
16.
by dougg3 2y ago
Ha! Guilty as charged. I have a coworker who's probably very disappointed in me right now!
17.
by dougg3 2y ago
To be fair, other non-cosmetic stuff uses the CPU percentage. This same bug was preventing fast user suspend on the OLPC until they worked around it. It was also a fun challenge.
18.
by dougg3 2y ago
Author here. Thanks! I believe the register reads are just extending the delay, although the new approach does have a side effect of reading from the hardware multiple times. I don't think the multiple reads really matter though. I wen
19.
by dougg3 2y ago
Thanks! I wouldn't want to write it any other way. I think it helps convey just how much work it really was.
20.
by dougg3 2y ago
I'm the author of this article and you're absolutely correct! This was a long, drawn-out project. For some context, I ordered the replacement regulators in February. The new LED driver chips were ordered in March, so that was arou
21.
by dougg3 2y ago
It lets you see the raw underlying packets like IN, OUT, SETUP, DATA0/1, etc. That capability would be most useful for USB device firmware developers who might want to see these packets to track down an issue with the DATA0/1 togg
22.
by dougg3 2y ago
Larry’s work on maintaining a bunch of Realtek’s vendor drivers on GitHub was huge for a lot of the community. Even today these forks often work much better than the mainline drivers. He will be missed! As others said, he was a huge inspira
23.
by dougg3 2y ago
Sorry, I somehow missed your comment until now. Didn't get any notifications. I tend to do it more like what you first said, mocking low-level calls. I typically put all hardware-specific code for one platform into its own directory. T
24.
by dougg3 2y ago
This is a really impressive project! It was a fun read. Thanks for sharing! I like this writing style. > As an aside, I try to create a dual-target build for all my embedded projects, with a native host build for rapid prototyping/d
25.
by dougg3 2y ago
Hi, I’m the author of this post. I’m not aware of a similar Pico project that acts as an Altera USB Blaster clone. Seems like an interesting project idea though! The CH552 firmware I used would provide a good sample to start from.
26.
by dougg3 2y ago
This same kind of thing happened to a family member several years ago on his Dell Inspiron 3650 minitower. Dell’s automatic updates installed a BIOS update (3.9.0) that bricked the computer. It would just power off and on automatically fore
27.
by dougg3 2y ago
Nice systemd solution, it seems very elegant! To be clear, my init script is named S00datetime, not 500datetime. It's actually the very first one that runs from rcS. So the date is restored very, very early in the boot process before p
28.
by dougg3 2y ago
Interesting, thanks for mentioning CUSE. If I’m understanding it correctly, it seems like it would be a perfect solution for this. Allows leaving the logic in userspace which is much easier to deal with (filesystem access, sharing the UART)
29.
by dougg3 2y ago
Author here. That's very much a fair point. I was thinking more from the perspective of firmware developers maintaining fixed userlands when I wrote that. It would definitely be an interesting challenge to figure out how to multiplex t
30.
by dougg3 2y ago
Ah, that’s another interesting possibility. I definitely observed that the actual HDMI refresh rate is 59.94 Hz while playing Super Mario Maker, but no idea what the game’s internal frame rate is.

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