Hello, On Fri, 17 Feb 2017 14:30:03 +0100, Gregory CLEMENT wrote:
> I have just tested it and as I feared, with HWBM enabled, a simple iperf > just doesn't work. And that's expected: the whole point of HWBM is that the buffer into which a RX packet is placed is allocated by the HW, and its address stored in the RX descriptor. So the following code: > > rx_desc->buf_phys_addr = phys_addr; > > i = rx_desc - rxq->descs; > > + rxq->buf_dma_addr[i] = phys_addr; Does not make sense, because it's not the SW that refills the RX descriptors with the address of the RX buffers. It's done by the HW. With HWBM, I believe you have no choice but to read the physical address from the RX descriptor. But you can probably optimize things a little bit by reading it only once, and then storing it into a cacheable variable. So maybe: - For SWBM, use the strategy proposed by Jisheng - For HWBM, at the beginning of the RX completion path, read once the rx_desc->buf_phys_addr, and store it in rxq->buf_dma_addr[index] Of course that's just a very rough proposal. I've been looking mainly at mvpp2 lately, and I'm not sure I still remember how mvneta works in the details. Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com