CanoScan LiDE 300 faster start
I was scanning a bunch of documents on my LiDE 300, and although it works flawlessly, I noticed that every single time, on start, it "calibrates" the head (starts rolling, brings it back, starts again, brings it back, and then starts the real scan). This takes approximately 3.5s. The official (windows) driver (via IJ Scan) doesn't do this calibration, or at least not every time.
I took a bunch of usb packet captures, and after a lot of debugging figured out that the scan_param
command (0xde20
) on address 0x05
, if it has 1, then it calibrates, if it has 0 it doesn't (starts fast). this line.
So what is the process to test this change on other devices and make sure it doesn't break anything? Or we can merge a patch for the LiDE 300 in particular?
Note: So even with the 0x05 set as 0 it still calibrates sometimes (maybe the hw decides after every few scans it needs to), but most of the time it doesn't. Also the original driver never sets the bit to 1, so in this regard it is safe (for this device at least).