Yes it is a firmware issue and not hardware issue. The so compatibility firmware just makes sure that the max packetsize follow the USB 2 specification and is 512 rather than 1024 bytes.
However, the issues are still remain. Switching to 8 Bit helps but there are also randomly issues (and it is for sure not the cable).
In 16 Bit mode it is like tossing a biased coin, towards not working.


./zwo_FWTool_USB2 -i ../../../firmware/USB2.0/ASI130MM.iic -t li2c
[36233.666737] usb 1-1.2: new high-speed USB device number 8 using ehci-pci
[36233.919714] usb 1-1.2: config 1 interface 0 altsetting 0 bulk endpoint 0x82 has invalid maxpacket 1024
[36233.921050] usb 1-1.2: New USB device found, idVendor=03c3, idProduct=130a, bcdDevice= 0.00
[36233.921054] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[36233.921056] usb 1-1.2: Product: ASI130MM
[36233.921058] usb 1-1.2: Manufacturer: ZWOptical company
[36233.921060] usb 1-1.2: SerialNumber: 00000

./zwo_FWTool_USB2 -i ../../../firmware/USB2.0/ASI130MM-compatible.iic -t li2c
[36214.974532] usb 1-1.2: new high-speed USB device number 6 using ehci-pci
[36215.188389] usb 1-1.2: New USB device found, idVendor=03c3, idProduct=130a, bcdDevice= 0.00
[36215.188393] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[36215.188395] usb 1-1.2: Product: ASI130MM
[36215.188397] usb 1-1.2: Manufacturer: ZWOptical company
[36215.188398] usb 1-1.2: SerialNumber: 00000

The binary diff between the two firmwares is:

$ cmp -l ASI130MM-compatible.iic ASI130MM.iic | awk '{printf "%08X %02X %02X\n", $1, strtonum(0$2), strtonum(0$3)}'
000001FA 02 04
000002A6 02 04
0000031A 02 04
0000038C 02 04
00000958 02 04
00000B48 02 04

One can for fun, change the "02" to "01", then the USB kernel layer complains:
config 1 interface 0 altsetting 0 bulk endpoint 0x82 has invalid maxpacket 256

Anyhow, it is still a shame, that ZWO is not able to fix the firmware. At least they could release the code and somebody would for
sure fix it for them. Just search on github.com for ASI120mm, you will find some projects reverse engineered the SDK library.

I am wondering how many INDI users had to sell (stop using) there 120/130mm cameras.
I bought a used Starlight Xpress guider and did not regret it. 130mm was my only and last ZWO product.

Interesting replies there, thanks all for sharing your experiences with Zwo - QHY products, I see that like on CloudyNight it's a toss up between the two brands. 
Some have great experience with one and bad ones with the other, and vice versa. The thing is as usual on the Internet we're always quick to complain about something broken but slow to praise something good.
 

I have been very happy with the 2nd-hand QHY183C I use with my Z61. I have encountered zero INDI/Ekos issues. The image scale would be a nice match to the Redcat, but you might be looking for a larger sensor even if it means larger pixels.

The compatibility firmware helps but it is not a true solution to the fundamental issue. Which is that the USB controller hardware sends non-standard packet sizes.
Those packets work ok on Windows because they are not handled as a security vulnerability the way the Linux kernel does.
Link rot is an issue, but I managed to dig up the old discussions I found on the issue.
bbs.astronomy-imaging-camera.com/d/6901
bbs.astronomy-imaging-camera.com/d/7132
I never managed to compile and install a custom kernel for myself. But it would be nice to know if someone can try and report back.

But the bottom line in regards to the main topic. I believe they would've fixed it if they could, so I would not hold it against them.

I did do this several years ago when I still had an ASI120MC (USB2). You need to install the kernel source package of Ubuntu, make the change to one of the C files (basically disable an error when the package size is invalid) and recompile. Then the camera worked for me. There were instructions somewhere (sorry, it's been a long time since I did this) and I am not sure if those instructions still work since the kernel source has evolved a lot since.

Just found this old thread from 2018 where I added a link to the kernel instructions but the link seems to be broken now:

indilib.org/forum/ccds-dslrs/2131-asi-12...ailes-to-expose.html

Hi all, my experience has been this. A few years ago i purchased a QHY163C. Initially everything was fine with using it with indi, but then QHY did a driver update and i was never able to get the thing to work. Even the cooling oscillated.

I rebuilt my computer(s) RPi4, tinkerboard, even my laptop, nothing helped.

After talking to QHY, their first response was does it work with Windows 10. I dont use windows so was never able to test it. It basically got to the point where i had to sell the camera because i just could not acquire or download photos.

I eventually bought a ZWO ASI 071 and have never had an issue with it using the same computer(s).

ZWO are on top of their game when it comes to drivers, but i suppose they have an interest in making sure things work under linux because they sell the ASI-AIR. QHY on the other hand, do not really seem to care about those who use anything linux.

Just my experience.

Thanks everyone for your inputs I decided to get the ZWO 183MM. Was going for the QHY model, but I will need that little hub at the back of ZWO camera.

Just advise before you commit to ASI183MM is to check your pixel resolution per arcsec astronomy.tools/calculators/ccd_suitability. The SONY 183MM/MC sensor has a very fine 2.4micron pixel size which I found it put my portable Z61 in a VERY sweet sport (and I LOVE IT) but causes oversampling with the C9.25 even with focal reducer (on which I use the larger pixel size ASI533 3.76micron and optimal seeing conditions)

Hello Mohamed,
I have a Redcat 51 which is 250mm and this is a very good match for the 183 chipset

In that case, I hope you enjoy it as I enjoy my little gems (Z61). Please share some of your 1st lights...

I own both ASI and QHY cameras.  

I do know that both ASI and QHY have the same sensors typically.  ASI tends to be more compatible with USB3.0, as with QHY it really needs specific hardware configurations to work properly.  QHY does seem to require a powered USB3.0 Hub as looking at the logs, I can see times where the QHY rejects connection due to power requirements.

I find that QHY offers more modes (typically 4 modes for the high end sensors).  I like that because I may use it on a brighter target, I can use the photographic mode, or sometimes I need high gain with a lower readout noise mode.  I can pick and choose which mode best suits my targets.
I know it is available on the QHY600m/c  QHY 268m/c QHY 367c.  

I also like that most QHY cameras come with dew heaters built into the housing.  I know ASI now typically offers this, but at the time, they did not.  on most cooled cameras QHY has a heater as standard equipment.  Very needed in my deep south Texas environment.

That's my take.

-Sonny


ASI does not offer this.