linux-kernel - [PATCH 0/2] PCI/PM: Elevate PM usage during reset probing

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Message-ID: <20250422230534.2295291-1-alex.williamson@redhat.com>
Date: Tue, 22 Apr 2025 17:05:30 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: bhelgaas@...gle.com,
	rafael@...nel.org
Cc: Alex Williamson <alex.williamson@...hat.com>,
	linux-pci@...r.kernel.org,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] PCI/PM: Elevate PM usage during reset probing

I encountered a confusing scenario where a device reports NoSoftRst- and
doesn't have any associated quirks to set PCI_DEV_FLAGS_NO_PM_RESET, but
it refuses to probe for PM reset support using the sysfs reset_method
attribute.  The reason turns out to be that we don't increment the usage
count while probing, the driver has the device in D3, where this system
seems to support D3cold, and the PM control register is read back as
0xffff.

The cleanup __free helper seems to be the cleanest solution here, versus
refactoring to a common exit point or wrappers around reset_fn, but feel
free to suggest otherwise.  I see a couple potential other use cases for
this helper in the vfio code.

Please review.  Thanks,

Alex

Alex Williamson (2):
  PM: runtime: Define pm_runtime_put cleanup helper
  PCI: Increment PM usage counter when probing reset methods

 drivers/pci/pci-sysfs.c    | 3 +++
 include/linux/pm_runtime.h | 2 ++
 2 files changed, 5 insertions(+)

-- 
2.48.1