TWx Linux Repository
f9ff68521a
The other day I was testing one of the HP laptops at my office with an i915/amdgpu hybrid setup and noticed that hotplugging was non-functional on almost all of the display outputs. I eventually discovered that all of the external outputs were connected to the amdgpu device instead of i915, and that the hotplugs weren't being detected so long as the GPU was in runtime suspend. After some talking with folks at AMD, I learned that amdgpu is actually supposed to support hotplug detection in runtime suspend so long as the OEM has implemented it properly in the firmware. On this HP ZBook 15 G4 (the machine in question), amdgpu wasn't managing to find the ATIF handle at all despite the fact that I could see acpi events being sent in response to any hotplugging. After going through dumps of the firmware, I discovered that this machine did in fact support ATIF, but that it's ATIF method lived in an entirely different namespace than this device's handle (the device handle was \_SB_.PCI0.PEG0.PEGP, but ATIF lives in ATPX's handle at \_SB_.PCI0.GFX0). So, fix this by probing ATPX's ACPI parent's namespace if we can't find ATIF elsewhere, along with storing a pointer to the proper handle to use for ATIF and using that instead of the device's handle. This fixes HPD detection while in runtime suspend for this ZBook! v2: Update the comment to reflect how the namespaces are arranged based on the system configuration. (Alex) Signed-off-by: Lyude Paul <lyude@redhat.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Cc: stable@vger.kernel.org |
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| ipc | ||
| kernel | ||
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| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.