On Wed, Jul 10, 2013 at 2:40 PM, Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote: > Well, it should work, ....
I tried forcing NET_IP_ALIGN to 0, and I did see the DMA accesses align on 32-bit boundaries with all the byte enables set. However, the memory corruption still occurred. > but it's possible that there is some subtle bug on this specific Freescale > SoC.... I looked through the Freescale errata (http://www.freescale.com/files/32bit/doc/errata/MPC8349ECE.pdf) and only 2 seem relevant: PCI19 and DMA2 (the rest are either fixed in our core version 3.1). PCI19: When using a dual-address cycle for inbound write accesses with then IOS is full, the PCI overwrites the address for the IOS with the new address from the bus. DMA2: There can be corruption of the DMA data. Examples are DAHTS is 8 bytes and the source port is a 32-bit PCI bus or the source memory space i son the PCI bus and is not prefetchable. I don't think PCI19 applies since no dual-address cycles are generated. From what I've seen, all the DMA addresses in the RX ring descriptors are in the lower 32-bit address space. I don't think DMA2 applies because it is for the DMA controller specific to the 8349. And since these transactions are not setup or managed by the DMA controller... At least I don't think they are (unless dma_alloc and dma_map_single do something related to this). My understanding is that in this case the PCI inbound registers are configured and the DMA controller is not used. > ...Did you correlate the corruption with one such packet ? > > Did you get any traces that show the flow that happens around a case of > corruption ? Not yet. I'm having a difficult time syncing the PCI trace with the kernel debug output. And since the corruption may be detected well after the actual corruption occurs, determine which DMA transfer caused a corruption is difficult. I'm still trying to gather more information. Thanks, Pete _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
