Hi Everyone,
We started working on "usb_dev_bulk" example from "starterware 2_0_1_1 version" and created a composite device by adding Mass storage device driver to access SD card in a board which uses AM3352 sitara processor.
The following are the issues that we came across
1) The Mass storage access is always put in DMA mode as specified in the example. So far, when we set the USB bulk device endpoints to be operated in DMA mode , we got errors whenever Mass storage event happens. The ARM hangs when servicing commands for mass storage driver, when the DMA for bulk device is enabled by using "enableCoreTx\RxDMA" function. But without DMA being set for bulk storage, we are able to use it. But for our application we require a very good throughput for both Rx and Tx and so we have to use DMA for bulk storage class.
2) The throughput that we have achieved so far is 17Mbps and 8Mbps for Tx and Rx endpoint through DMA mode using bulk device class driver. For Tx we have been able to set GRNDIS option but for Rx we had to stick with Transparent itself. I would like to know what is the general through that can be achieved for Tx and Rx using Bulk device driver in DMA.
Please do share your experience and thoughts on the above two points, which possibly will help me to solve them.
Thanks In Advance
Kandhasamy