On 2019-10-23 02:24, Adrian Chadd wrote:
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
DMA engine is working as expected as the configuration. It's copy engine
which actually
splits the RD/WR requests and accesses host memory.
And yes it's platform related configuration. We have never hit this
issue on x86 platform.
Zhi
