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Lyude authored
commit 23a1a9e5 upstream. Just about all of amdgpu's connector probing functions try to acquire runtime PM refs. If we try to do this in the context of amdgpu_resume_kms by calling drm_helper_hpd_irq_event(), we end up deadlocking the system. Since we're guaranteed to be holding the spinlock for RPM in amdgpu_resume_kms, and we already know the GPU is in working order, we need to prevent the RPM helpers from trying to run during the initial connector reprobe on resume. There's a couple of solutions I've explored for fixing this, but this one by far seems to be the simplest and most reliable (plus I'm pretty sure that's what disable_depth is there for anyway). Reproduction recipe: - Get any laptop dual GPUs using PRIME - Make sure runtime PM is enabled for amdgpu - Boot the machine - If the machine managed to boot without hanging, switch out of X to another VT. This should definitely cause X to hang infinitely. Changes since v1: - add appropriate #ifdef checks for CONFIG_PM. This is not very useful, but it appears some kernel test suites test compiling amdgpu with CONFIG_PM disabled, which results in this patch breaking the builds if we don't include this #ifdef Cc: Alex Deucher <alexdeucher@gmail.com> Reviewed-by:
Alex Deucher <alexander.deucher@amd.com> Signed-off-by:
Lyude <cpaul@redhat.com> Signed-off-by:
Alex Deucher <alexander.deucher@amd.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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