From: Stephen Warren <swarren@wwwdotorg.org>
To: Eric Anholt <eric@anholt.net>
Cc: linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Lee Jones <lee@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jason Cooper <jason@lakedaemon.net>,
Marc Zyngier <marc.zyngier@arm.com>
Subject: Re: [PATCH 4/4] irqchip: bcm2836: Use a more generic memory barrier call
Date: Fri, 8 Apr 2016 23:26:22 -0600 [thread overview]
Message-ID: <5708927E.9030406@wwwdotorg.org> (raw)
In-Reply-To: <87a8l40xox.fsf@eliezer.anholt.net>
On 04/08/2016 12:20 PM, Eric Anholt wrote:
> Stephen Warren <swarren@wwwdotorg.org> writes:
>
>> On 04/04/2016 09:44 PM, Eric Anholt wrote:
>>> dsb() requires an argument on arm64, so we needed to add "sy".
>>> Instead, take this opportunity to switch to the same smp_wmb() call
>>> that gic uses for its IPIs. This is a less strong barrier than we
>>> were doing before (dmb(ishst) compared to dsb(sy)), but it seems to be
>>> the correct one.
>>
>> I assume all MMIO is part of the ish domain?
>>
>> If so, the series,
>> Acked-by: Stephen Warren <swarren@wwwdotorg.org>
>
> I don't know if this barrier implies ordering all the way out to AXI on
> this HW, but I don't think that's a requirement of this function.
My understanding was that the barrier was explicitly to work around a
bug in the bus fabric of the SoC, and hence the barrier very much does
have to affect the transaction all the way out to AXI. Re-reading
BCM2835-ARM-Peripherals.pdf section 1.3 "Peripheral access precautions
for correct memory ordering" seems to confirm this.
next prev parent reply other threads:[~2016-04-09 5:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 3:44 [PATCH 0/4] irqchip: bcm2835: arm64 port Eric Anholt
2016-04-05 3:44 ` [PATCH 1/4] irqchip: bcm2835: Avoid arch/arm-specific handle_IRQ Eric Anholt
2016-04-05 3:44 ` [PATCH 2/4] irqchip: bcm2836: Drop smp_set_ops on arm64 builds Eric Anholt
2016-04-05 13:44 ` Marc Zyngier
2016-04-08 20:43 ` Arnd Bergmann
2016-04-13 19:49 ` Eric Anholt
2016-04-05 3:44 ` [PATCH 3/4] irqchip: bcm2836: Fix compiler warning on 64-bit build Eric Anholt
2016-04-05 3:44 ` [PATCH 4/4] irqchip: bcm2836: Use a more generic memory barrier call Eric Anholt
2016-04-06 4:59 ` Stephen Warren
2016-04-08 18:20 ` Eric Anholt
2016-04-09 5:26 ` Stephen Warren [this message]
2016-04-10 18:32 ` Eric Anholt
2016-04-11 15:52 ` Stephen Warren
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