Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
2ef6efa79f
When DMAR / VT-d is enabled, the display engine uses overfetching, presumably to deal with the increased latency. To avoid display engine errors and DMAR faults, as a workaround the GGTT is populated with scatch PTEs when VT-d is enabled. However starting with gen10, Write-combined writing of scratch PTES is no longer possible and as a result, populating the full GGTT with scratch PTEs like on resume becomes very slow as uncached access is needed. Therefore, on integrated GPUs utilize the fact that the PTEs are stored in stolen memory which retain content across S3 suspend. Don't clear the PTEs on suspend and resume. This improves on resume time with around 100 ms. While 100+ms might appear like a short time it's 10% to 20% of total resume time and important in some applications. One notable exception is Intel Rapid Start Technology which may cause stolen memory to be lost across what the OS percieves as S3 suspend. If IRST is enabled or if we can't detect whether IRST is enabled, retain the old workaround, clearing and re-instating PTEs. As an additional measure, if we detect that the last ggtt pte was lost during suspend, print a warning and re-populate the GGTT ptes On discrete GPUs, the display engine scans out from LMEM which isn't subject to DMAR, and presumably the workaround is therefore not needed, but that needs to be verified and disabling the workaround for dGPU, if possible, will be deferred to a follow-up patch. v2: - Rely on retained ptes to also speed up suspend and resume re-binding. - Re-build GGTT ptes if Intel rst is enabled. v3: - Re-build GGTT ptes also if we can't detect whether Intel rst is enabled, and if the guard page PTE and end of GGTT was lost. v4: - Fix some kerneldoc issues (Matthew Auld), rebase. Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220617152856.249295-1-thomas.hellstrom@linux.intel.com |
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| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text 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.