On 7/18/19 5:31 AM, Christoph Hellwig wrote:
On Tue, Jul 16, 2019 at 10:43:33PM -0400, Al Farleigh wrote:
re: the dma-direct code commit below
I have bisected the kernel to isolate a PCI board problem on my AMD x86-64
ASROCK system. The board worked at (Fedora kernel) 4.18.16 but stopped when
moving to (Fedora kernel) 5.0. I then used (git/torvalds/linux) 4.20-rc4 or
so to locate the fault via bisect.
I now have two kernels, good/bad, that straddle the commit.
I was asked to try v5.2 just in case it was fixed; I compiled it and the
fault appears to still be present.
Simply, mpeg video does not stream from board; no errors, but no video.
My work is documented at
https://bugs.kde.org/show_bug.cgi?id=408004
I've looked through that log but I'm still not sure what driver
you are actually using for video capture. Am I right in that your
are using the saa7134 driver based on the dmesg?
That driver uses a 32-bit DMA mask, so we should be bounce buffering.
We recently had a bug with the AMD memory encryption and the encrypted
bit, are you using that? The "Freeing unused decrypted memory:" message
somehow suggests that but I can't find where that would come from by a
simple grep. If your are using AMD memory encryption or are not sure
please try the patch below:
Hello; I installed the patch on v5.2, verified by eye it got applied,
recompiled, and found no change; that is, the video stream doesn't display.
I also went back and verified my known good v4.20-rc4 kernel still
worked, and my known bad v4.20-rc4 stayed bad. No changes.
I will note that the video has once or twice but extremely rarely had
started on the bad kernels; maybe a timing or race, or somehow being set
up from a previous boot; I try to power off between tests to make sure
system starts from a known, uncontaminated environment.
Regards, Al Farleigh
---
From 9087c37584fb7d8315877bb55f85e4268cc0b4f4 Mon Sep 17 00:00:00 2001
From: Tom Lendacky <[email protected]>
Date: Wed, 10 Jul 2019 19:01:19 +0000
Subject: dma-direct: Force unencrypted DMA under SME for certain DMA masks
_______________________________________________
iommu mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/iommu
