On Mon, 21 Feb 2005, mohanlal jangir wrote: > Could someone tell me the difference between "dCBWDataTransferLength" field > of CBW and "Transfer Length" field of CBWCB (e.g. READ(10) )?
dCBWDataTransferLength is the number of bytes to be transferred in the data stage. The "Transfer Length" field is the number of bytes, or the number of blocks, or the number of something else, depending on which SCSI command is in the CBWCB. > Another question is; Do we need to have DMA capable memory allocated for > reading data from a USB mass storage device? Yes, you need to use DMA-capable memory for reading (or writing) data from a USB device. As a general rule kmalloc() will give you want you want. But you can also use usb_buffer_alloc(). (Note that the GFP_DMA flag is _not_ necessary.) Alan Stern ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
