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478689b599
The recent regression report revealed that the use of WC pages for AMD
HDMI device together with AMD IOMMU leads to unexpected truncation or
noises. The issue seems triggered by the change in the kernel core
memory allocation that enables IOMMU driver to use always S/G
buffers. Meanwhile, the use of WC pages has been a workaround for the
similar issue with standard pages in the past. So, now we need to
apply the workaround conditionally, namely, only when IOMMU isn't in
place.
This patch modifies the workaround code to check the DMA ops at first
and apply the snoop-off only when needed.
Fixes: f5ff79fddf ("dma-mapping: remove CONFIG_DMA_REMAP")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219087
Link: https://patch.msgid.link/20240731170521.31714-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.