Hi George, Thanks for having a look! On 05/23/2014 01:24 PM, George Cherian wrote: > On 5/23/2014 3:01 PM, Daniel Mack wrote: >> The musb/cppi41 glue layer is capable of handling transactions that span >> over more than one USB packet by reloading the DMA descriptors >> partially. An urb is considered completed when either its transfer >> buffer has been filled entirely (actual_length == >> transfer_buffer_length) or if a packet in the stream has less bytes than >> the endpoint's wMaxPacketSize. > Can you explain a bit more. Sure. > Doesn't it checks for > actual_length + xfer_len >= transfer_buffer_length ? > > This check is also failing? Yes. For the driver I'm testing with, transfer_buffer_length is 16k. Assume wMaxPacketSize == 512 and the following sequence of incoming packet sizes: 512, 512, 384. The URB should be given back after the 384 packet has been received, with an effective total length of 1408 bytes. The code in musb_cppi41.c does the right thing by not reloading a new DMA descriptor but calling musb_dma_completion() from cppi41_trans_done(). However, both checks for 'done' that the core currently looks at a false in that case (musb_host.c, ~ line 1740): done = (urb->actual_length + xfer_len >= urb->transfer_buffer_length || dma->actual_len < qh->maxpacket); ... because dma->actual_len is already 1408, and hence the maxpacket size check doesn't make sense in such cases. This is why I added a new flag to overrule that decision from the cppi41 glue layer. HTH, Daniel -- 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
