USB 2.0 transfer (or sector) size limit breaks Vuescan
 

Vuescan 8.3.87 does not recognize a Minolta Scan Dual III scanner through a USB 2.0 port on an add-on PCI card on a desktop machine with a fresh install of FC5 updated via yum (kernel 2.6.18-1.2257.fc5). Connecting the scanner to the motherboard's USB 1.0 ports results in proper function. An exchange of emails with the developer of Vuescan concludes: "This would indicate a kernel problem . . ., probably in the USB subsystem limiting transfers to 32 KBytes." "The problem is that when VueScan tries to load the firmware into the scanner, it tries to transfer 44904 bytes in a single transfer. This is failing."

Where is the USB 2.0 max sector or transfer size limit established? In the kernel structure or a kernel module? Does changing it involve hand-editing a module (ehci_hcd?) or adjusting a parameter when configuring the kernel prior to compiling? I've dug around quite a bit for an answer to this, but no luck so far. Either the answer is so well known as to not be worthy of comment, or the Vuescan => Dual III communication is unusual.