[PATCH v4 0/5] irqchip/imx-irqsteer: Allow building as module

From: Zhipeng Wang <[email protected]>

This series makes the i.MX IRQSTEER driver buildable as a module.

v3 was a four-patch series: three fixes for pre-existing bugs that only
become reachable once the driver can be unbound/reloaded, followed by
the module conversion. On v3, Frank Li reviewed the unload-path fixes
and asked for three changes, all addressed here:

 - The probe() error-path irq_domain leak was fixed by hand-rolling an
   err_domain label. Frank suggested a devres-managed domain instead,
   and to add a reusable devm_irq_domain_create_linear() helper so other
   drivers benefit. Patch 1/5 adds that helper (the devres sibling of
   irq_domain_create_linear()); patch 2/5 switches imx-irqsteer to it,
   which fixes the leak structurally and lets remove() drop its explicit
   irq_domain_remove().

 - Frank questioned why remove() disposed of the mappings "twice". The
   two loops disposed of two different sets: the parent output mappings
   the driver created with irq_of_parse_and_map(), and the child input
   mappings the domain handed out. The child mappings are freed by their
   consumers and, with the domain now owned by devres, are torn down
   automatically; only the parent mappings need explicit disposal. Patch
   3/5 disposes of the parent mappings only, dropping the child loop.

 - Frank pointed out that masking in remove() touches CHANMASK while the
   device may be runtime-suspended with the clock gated. The remove()
   masking is unnecessary: the next probe() quiesces the hardware before
   it re-maps and unmasks the parent interrupts, which is the only window
   in which a stale line could storm. Patch 4/5 therefore masks only in
   probe().

Patch 5/5 then converts the driver to a module. As in v3, it lets devres
own the clock and runtime PM (devm_clk_get_enabled() +
devm_pm_runtime_set_active_enabled()).

Changes in v4:
 - New patch 1/5: add devm_irq_domain_create_linear() (Frank Li).
 - Patch 2/5 (was "Fix error handling path in probe()"): use the new
   devm helper to manage the domain instead of hand-rolling an
   err_domain label; remove() drops irq_domain_remove() (Frank Li).
 - Patch 3/5 (was 2/4): dispose of the parent mappings only; the child
   mapping disposal loop is removed (Frank Li).
 - Patch 4/5 (was 3/4): mask interrupts in probe() only; the remove()
   masking, which could touch registers while runtime-suspended, is
   dropped (Frank Li).
 - Patch 5/5 (was 4/4): no functional change; remove() and the probe()
   error path now only dispose of the parent mappings.

v3: https://lore.kernel.org/r/[email protected]
v2: https://lore.kernel.org/r/[email protected]
v1: https://lore.kernel.org/r/[email protected]

Jindong Yue (1):
  irqchip/imx-irqsteer: Allow building as module

Zhipeng Wang (4):
  genirq/irqdomain: Add devm_irq_domain_create_linear()
  irqchip/imx-irqsteer: Use devm to manage the IRQ domain
  irqchip/imx-irqsteer: Dispose of parent IRQ mappings in remove()
  irqchip/imx-irqsteer: Mask all interrupts in probe()

 drivers/irqchip/Kconfig            |  2 +-
 drivers/irqchip/irq-imx-irqsteer.c | 52 +++++++++++++++++++-----------
 include/linux/irqdomain.h          | 30 +++++++++++++++++
 3 files changed, 64 insertions(+), 20 deletions(-)


base-commit: bd5f485f3f026225b86573e559af0b7254ef4184
-- 
2.34.1