tree beb95f1d6e8d29a87a593bf25030404b9d17671b
parent 38dbfb59d1175ef458d006556061adeaa8751b72
author Will Deacon <will.deacon@arm.com> 1392918127 +0000
committer Arnd Bergmann <arnd@arndb.de> 1393353363 +0100

irqchip: gic: use dmb ishst instead of dsb when raising a softirq

When sending an SGI to another CPU, we require a barrier to ensure that
any pending stores to normal memory are made visible to the recipient
before the interrupt arrives.

Rather than use a vanilla dsb() (which will soon cause an assembly error
on arm64) before the writel_relaxed, we can instead use dsb(ishst),
since we just need to ensure that any pending normal writes are visible
within the inner-shareable domain before we poke the GIC.

With this observation, we can then further weaken the barrier to a
dmb(ishst), since other CPUs in the inner-shareable domain must observe
the write to the distributor before the SGI is generated.

Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>