[PATCH v3 0/6] watchdog: starfive: runtime PM cleanup

[William Theesfeld <william@theesfeld.net>]

This series addresses runtime PM correctness issues in the StarFive
watchdog driver.  v3 fixes three issues that were raised against v2:

Changes in v3:
- 2/6 (pm_runtime_put_sync positive return): the v2 commit message
  and code comment described the semantics of a "1" return as "the
  device is still in use", which is wrong — that case is signalled
  by -EAGAIN.  A positive return indicates a non-error condition such
  as the device already being in the requested state.  Reword both
  the commit message and the in-function comment to describe this
  correctly.  No code change beyond that.

- 3/6 (probe error path restructure): the v2 patch left a path that
  put the runtime PM usage counter twice.  When the success-path
  pm_runtime_put_sync() (line ~513) returns an error, the function
  jumps to err_unregister_wdt.  In v2 that label fell through to
  err_put_pm, which called pm_runtime_put_sync() a second time on a
  counter that had already been decremented by the first put.
  Insert an explicit "goto err_pm_disable;" after the unregister so
  the post-register error path skips the second put.

- 4/6 (system suspend/resume guard): the v2 patch added a
  pm_runtime_status_suspended() check on the resume path but kept
  the final restart predicate as watchdog_active().  For watchdogs
  started via early_enable, the framework state is WDOG_HW_RUNNING
  without WDOG_ACTIVE, so the existing predicate left the hardware
  permanently stopped after a system suspend/resume cycle (the
  matching suspend path had already stopped it).  Extend the
  predicate to also accept watchdog_hw_running().

Patches 1, 5, and 6 are unchanged from v2.

Several pre-existing issues in adjacent code paths were flagged
during v2 review (hardware access during driver unbind, possible
races between device_shutdown() and the watchdog reboot notifier,
SETTIMEOUT/GETTIMELEFT ioctls touching gated registers).  They are
not addressed in this series; each is a separate logical change
that deserves its own patch and its own justification.  Happy to
follow up on any the maintainers want addressed first.

The whole series builds cleanly with CONFIG_STARFIVE_WATCHDOG=m on
x86_64 defconfig.  Runtime testing would require StarFive JH7100 /
JH7110 hardware and has not been performed.

William Theesfeld (6):
  watchdog: starfive: balance PM refcount when start operation fails
  watchdog: starfive: treat pm_runtime_put_sync() positive return as
    success
  watchdog: starfive: balance PM refcount and disable in probe error
    paths
  watchdog: starfive: guard system suspend/resume hardware access
  watchdog: starfive: avoid PM refcount underflow in shutdown
  watchdog: starfive: release early_enable PM refcount on remove

 drivers/watchdog/starfive-wdt.c | 109 ++++++++++++++++++++++++++------
 1 file changed, 89 insertions(+), 20 deletions(-)

-- 
2.54.0