[PATCH 0/1] fix MVEBU GPIO driver bug causing kernel hang

[Gerlando Falauto]

The MVEBU GPIO driver (like the old orion-gpio) is affected by a subtle
bug, where requesting (and triggering) both EDGE- and LEVEL- based IRQs
causes the kernel to hang.
Part of the reworking necessary to fix this bug (i.e. handling two
separate mask registers, one per chip type) was first submitted by me,
then reworked by Thomas Gleixner, then mainlined, finally landing in 3.11.

The final bits to actually fix this are still missing though.
This patch will fix this.
I also marked the necessary prerequisites to apply this to linux-stable.

SIDE NOTE: If I understand correctly, a brand new driver from
Sebastian Hesselbarth (drivers/irqchip/irq-orion.c) may replace this driver
in the future, but it still misses the IRQ_GC_MASK_CACHE_PER_TYPE bit:

static int __init orion_bridge_irq_init(struct device_node *np,
                                       struct device_node *parent)
{
[...]
       ret = irq_alloc_domain_generic_chips(domain, nrirqs, 1, np->name,
                            handle_level_irq, clr, 0, IRQ_GC_INIT_MASK_CACHE);

Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Linus Walleij <linus.walleij at stericsson.com>
Cc: Andrew Lunn <andrew at lunn.ch>
Cc: Jason Cooper <jason at lakedaemon.net>
Cc: Gregory Clement <gregory.clement at free-electrons.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com>
Cc: Linus Walleij <linus.walleij at linaro.org>
Cc: Andrew Lunn <andrew at lunn.ch>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: linux-arm-kernel at lists.infradead.org
#Cc: <stable at vger.kernel.org> # 3.7.x cfeaa93 genirq: Generic chip: Remove the local cur_regs() function
#Cc: <stable at vger.kernel.org> # 3.7.x 899f0e6 genirq: Generic chip: Add support for per chip type mask cache
#Cc: <stable at vger.kernel.org> # 3.7.x af80b0f genirq: Generic chip: Handle separate mask registers

Gerlando Falauto (1):
  gpio: mvebu: enable and use IRQ_GC_MASK_CACHE_PER_TYPE

 drivers/gpio/gpio-mvebu.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

-- 
1.8.0.1