From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
iommu@lists.linux-foundation.org,
Douglas Anderson <dianders@chromium.org>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/arm-smmu: Demote error messages to debug in shutdown callback
Date: Fri, 27 Mar 2020 20:39:46 +0530 [thread overview]
Message-ID: <37db9a4d524aa4d7529ae47a8065c9e0@codeaurora.org> (raw)
In-Reply-To: <0023bc68-45fb-4e80-00c8-01fd0369243f@arm.com>
Hi Robin,
Thanks for taking a look at this.
On 2020-03-27 19:42, Robin Murphy wrote:
> On 2020-03-27 1:28 pm, Sai Prakash Ranjan wrote:
>> Currently on reboot/shutdown, the following messages are
>> displayed on the console as error messages before the
>> system reboots/shutdown.
>>
>> On SC7180:
>>
>> arm-smmu 15000000.iommu: removing device with active domains!
>> arm-smmu 5040000.iommu: removing device with active domains!
>>
>> Demote the log level to debug since it does not offer much
>> help in identifying/fixing any issue as the system is anyways
>> going down and reduce spamming the kernel log.
>
> I've gone back and forth on this pretty much ever since we added the
> shutdown hook - on the other hand, if any devices *are* still running
> in those domains at this point, then once we turn off the SMMU and let
> those IOVAs go out on the bus as physical addresses, all manner of
> weirdness may ensue. Thus there is an argument for *some* indication
> that this may happen, although IMO it could be downgraded to at least
> dev_warn().
>
Any pointers to the weirdness here after SMMU is turned off?
Because if we look at the call sites, device_shutdown is called
from kernel_restart_prepare or kernel_shutdown_prepare which would
mean system is going down anyways, so do we really care about these
error messages or warnings from SMMU?
arm_smmu_device_shutdown
platform_drv_shutdown
device_shutdown
kernel_restart_prepare
kernel_restart
Thanks,
Sai
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next prev parent reply other threads:[~2020-03-27 15:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-27 13:28 [PATCH] iommu/arm-smmu: Demote error messages to debug in shutdown callback Sai Prakash Ranjan
2020-03-27 14:12 ` Robin Murphy
2020-03-27 15:09 ` Sai Prakash Ranjan [this message]
2020-03-27 16:17 ` Rob Clark
2020-03-27 18:18 ` Sai Prakash Ranjan
2020-03-27 19:02 ` Robin Murphy
2020-03-28 7:35 ` Sai Prakash Ranjan
2020-03-30 18:24 ` Doug Anderson
2020-03-31 7:36 ` Sai Prakash Ranjan
2020-03-31 7:44 ` Will Deacon
2020-03-31 7:53 ` Sai Prakash Ranjan
2020-04-22 19:49 ` Doug Anderson
2020-04-23 8:17 ` Sai Prakash Ranjan
2020-04-23 9:28 ` Robin Murphy
2020-04-23 9:41 ` Sai Prakash Ranjan
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