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From: Stephen Boyd <swboyd@chromium.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Rajendra Nayak <rnayak@codeaurora.org>,
	Robin Murphy <robin.murphy@arm.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Andy Gross <agross@kernel.org>,
	linux-arm-msm@vger.kernel.org, Will Deacon <will@kernel.org>,
	linux-arm-msm-owner@vger.kernel.org
Subject: Re: [PATCHv6 3/3] iommu: arm-smmu-impl: Add sdm845 implementation hook
Date: Thu, 19 Sep 2019 13:00:51 -0700
Message-ID: <5d83de74.1c69fb81.71c0f.f162@mx.google.com> (raw)
In-Reply-To: <081fff2f5dacfa7b6f5df6364f088045@codeaurora.org>

Quoting Sai Prakash Ranjan (2019-09-19 11:54:27)
> On 2019-09-19 08:48, Sai Prakash Ranjan wrote:
> > On 2019-09-19 05:55, Bjorn Andersson wrote:
> >> In the transition to this new design we lost the ability to
> >> enable/disable the safe toggle per board, which according to Vivek
> >> would result in some issue with Cheza.
> >> 
> >> Can you confirm that this is okay? (Or introduce the DT property for
> >> enabling the safe_toggle logic?)
> >> 
> > 
> > Hmm, I don't remember Vivek telling about any issue on Cheza because
> > of this logic.
> > But I will test this on Cheza and let you know.
> > 
> 
> I tested this on Cheza and no perf degradation nor any other issue is 
> seen
> atleast openly, although I see this below stack dump always with 
> cant_sleep change added.

The usage of cant_sleep() here is wrong then, and the comment should be
removed from the scm API as well because it looks like it's perfectly OK
to call the function from a context that can sleep.

> 
> [    5.048860] BUG: assuming atomic context at 
> /mnt/host/source/src/third_party/kernel/v5.3/drivers/firmware/qcom_scm-64.c:206
> [    5.060303] in_atomic(): 0, irqs_disabled(): 0, pid: 1, name: 
> swapper/0
> [    5.067118] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.3.0 #102
> [    5.073299] Hardware name: Google Cheza (rev3+) (DT)
> [    5.078416] Call trace:
> [    5.080953]  dump_backtrace+0x0/0x16c
> [    5.084727]  show_stack+0x20/0x2c
> [    5.088156]  dump_stack+0x90/0xcc
> [    5.091585]  __cant_sleep+0xb4/0xc4
> [    5.095192]  __qcom_scm_qsmmu500_wait_safe_toggle+0x5c/0xa0
> [    5.100929]  qcom_scm_qsmmu500_wait_safe_toggle+0x28/0x34
> [    5.106491]  qcom_sdm845_smmu500_reset+0x24/0x50
> [    5.111249]  arm_smmu_device_reset+0x1a4/0x25c
> [    5.115827]  arm_smmu_device_probe+0x418/0x50c
> [    5.120406]  platform_drv_probe+0x90/0xb0
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Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-17  9:45 [PATCHv6 0/3] QCOM smmu-500 wait-for-safe handling for sdm845 Sai Prakash Ranjan
2019-09-17  9:45 ` [PATCHv6 1/3] firmware: qcom_scm-64: Add atomic version of qcom_scm_call Sai Prakash Ranjan
2019-09-19  0:50   ` Stephen Boyd
2019-09-17  9:45 ` [PATCHv6 2/3] firmware/qcom_scm: Add scm call to handle smmu errata Sai Prakash Ranjan
2019-09-19  0:53   ` Stephen Boyd
2019-09-17  9:45 ` [PATCHv6 3/3] iommu: arm-smmu-impl: Add sdm845 implementation hook Sai Prakash Ranjan
2019-09-19  0:25   ` Bjorn Andersson
2019-09-19  0:52     ` Stephen Boyd
2019-09-19  3:18     ` Sai Prakash Ranjan
2019-09-19 18:54       ` Sai Prakash Ranjan
2019-09-19 20:00         ` Stephen Boyd [this message]
2019-09-20  7:54           ` Sai Prakash Ranjan
2019-09-19  0:57   ` Stephen Boyd
2019-09-19  3:13     ` Sai Prakash Ranjan

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