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quirk_nvidia_hda() forcefully enables HDA controller on all NVIDIA GPUs, because some buggy BIOSes leave it disabled. However, some dual-GPU laptops do not have a functional HDA controller in DGPU, and BIOS disables it on purpose. After quirk_nvidia_hda() reenables this dummy HDA controller, attempting to probe it fails at azx_first_init(), which is too late to cancel the probe, as it happens in azx_probe_continue(). The sna_hda_intel driver calls azx_free() and stops the chip, however, it stays probed, and from the runtime PM point of view, the device remains active (it was set as active by the PCI subsystem on probe). It prevents vga_switcheroo from turning off the DGPU, because pci_create_device_link() syncs power management for video and audio devices. Affected devices should be added to driver_denylist to prevent them from probing early. This patch helps identify such devices by printing a warning, and also forces the device to the suspended state to allow vga_switcheroo turn off DGPU. Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com> Link: https://patch.msgid.link/20250208214602.39607-2-maxtram95@gmail.com 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
``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 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.