[RFC,0/1] Avoid parent bridge rpm on mmap mappings

Message

Gupta, Anshuman Aug. 8, 2022, 10:35 a.m. UTC

RFC proposal to get community feedback to handle the lmem
mmap memory mappings. We can have two solutions.

1. Avoid rpm for any mmap mapping.
2. Update the page tables while entering to runtime suspend to raise
   a page fault while device in D3.

Solution 2 will incur huge latency versus solution 1 which effectively 
disable the runtime PM.

Caveat with solution 1 that, it doesn't address the case when user 
directly maps PCI Bar resource i.e. below mentioned resource. 
"/sys/bus/pci/devices/0000\:03\:00.0/resource2" 

Anshuman Gupta (1):
  drm/i915/dgfx: Avoid parent bridge rpm on mmap mappings

 drivers/gpu/drm/i915/gem/i915_gem_mman.c | 11 ++++++++
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c  |  8 ++++++
 drivers/gpu/drm/i915/intel_runtime_pm.c  | 35 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_runtime_pm.h  |  2 ++
 4 files changed, 56 insertions(+)