Hi there, I'm in the process of designing a VME=>USB interface, and I wanted to use the FT232H, but according to FTDI, the throughput on Linux is only ~9MBytes/sec using current kernels. In the past, it was ~40MBytes/sec. Sadly my Arm board is delivered running Linux 3.4.29 I don't really want to go back to the "olden days" of kernel 2.6.27-57 - I'm not even sure it's possible on my embedded ARM board, so I was wondering if anyone knew the reasons for such a drastic bandwidth reduction. If it's something I can live with in my embedded situation, I'd prefer to revert the change and lose whatever functionality was gained by slashing the bandwidth by 4. Basically I need to be able to put 20 MBytes/sec through the USB port. The FT232H parts are very attractive because they offer a simple FIFO-style interface and one doesn't have to implement an entire USB stack, which is much harder when you don't have a CPU ... Cheers Simon. Mail from FTDI: ---8<---8<---8<--- C u t h e r e ---8<---8<---8<--- Simon: You could use Sync FIFO mode, but I’m afraid there is another “gotcha” to be aware of - with newer Linux kernels (>2.6.28-3), Sync FIFO throughput is limited to 9 MByte/sec With the older kernels (2.6.27-57 and older) Sync FIFO will run at 40 MByte/sec. Since you are using ARM Linux, there is a good chance you have an older kernel. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
