On Tue, 22 Oct 2019 at 10:17, Peter Oh <peter.oh@xxxxxxxx> wrote: > > > On 10/22/19 1:57 AM, Zhi Chen wrote: > > This reverts commit 76d164f582150fd0259ec0fcbc485470bcd8033e. > > PCIe hung issue was observed on multiple platforms. The issue was reproduced > > when DUT was configured as AP and associated with 50+ STAs. > > > > With PCIe protocol analyzer, we can see DMA Read crossing 4KB boundary when > > issue happened. It broke PCIe spec and caused PCIe stuck. > > How can you say value 0 (I believe it's 64 bytes) DMA burst size causes > the symptom and 1 fixes it? +1 to this question. Also, shouldn't the DMA engine be doing what the firmware says? Is the firmware/copy engine actually somehow bursting / prefetching across a 4K page boundary? Surely this is something that can be fixed in software/firmware by correctly configuring up buffer size/offsets? -adrian
