From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>
Subject: Re: [PATCH 1/2] iommu/rockchip: Handle errors returned from PM
	framework
Date: Tue, 7 Aug 2018 13:31:49 +0100
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	<20180807085406.3863-2-marc.zyngier@arm.com> <2940317.dDZy1L4CDY@phil>
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To: Heiko Stuebner <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>
Cc: Jeffy Chen <jeffy.chen-TNX95d0MmH7DzftRWevZcw@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
List-Id: linux-rockchip.vger.kernel.org

On 07/08/18 13:09, Heiko Stuebner wrote:
> Hi Marc,
> 
> Am Dienstag, 7. August 2018, 10:54:05 CEST schrieb Marc Zyngier:
>> pm_runtime_get_if_in_use can fail: either PM has been disabled
>> altogether (-EINVAL), or the device hasn't been enabled yet (0).
>> Sadly, the Rockchip IOMMU driver tends to conflate the two things
>> by considering a non-zero return value as successful.
>>
>> This has the consequence of hiding other bugs, so let's handle this
>> case throughout the driver, with a WARN_ON_ONCE so that we can try
>> and work out what happened.
>>
>> Fixes: 0f181d3cf7d98 ("iommu/rockchip: Add runtime PM support")
>> Signed-off-by: Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>
> 
> I'm still not sure about the !CONFIG_PM case, as it was probably silently
> working in that case before

Do we agree that this is an orthogonal problem though?

> 
> But on the other hand we're also already running over it in other places
> like in the iommu-shutdown and I guess if someone _really_ disabled
> CONFIG_PM, a lot of additional stuff would fail anyway.
> 
> So should we wrap that in some #ifdef magic, just ignore it or simply
> select PM similar to what Tegra, Renesas and Vexpress seem to do?
> 
> I guess I like the 3rd option best ;-)

It probably doesn't hurt. At what level do you want it? As a dependency
to the IOMMU? or to the platform?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...