linux-kernel - Re: [PATCH] venus: core: add shutdown callback for venus

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Message-ID: <7223de0f80de73835238abe13a79d1bc@codeaurora.org>
Date:   Wed, 24 Jun 2020 12:17:07 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Mansur Alisha Shaik <mansur@...eaurora.org>
Cc:     stanimir.varbanov@...aro.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, vgarodia@...eaurora.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH] venus: core: add shutdown callback for venus

Hi Mansur,

On 2020-06-13 16:03, Mansur Alisha Shaik wrote:
> After the SMMU translation is disabled in the
> arm-smmu shutdown callback during reboot, if
> any subsystem are still alive then IOVAs they
> are using will become PAs on bus, which may
> lead to crash.
> 
> Below are the consumers of smmu from venus
> arm-smmu: consumer: aa00000.video-codec supplier=15000000.iommu
> arm-smmu: consumer: video-firmware.0 supplier=15000000.iommu
> 
> So implemented shutdown callback, which detach iommu maps.
> 
> Change-Id: I0f0f331056e0b84b92f1d86f66618d4b1caaa24a
> Signed-off-by: Mansur Alisha Shaik <mansur@...eaurora.org>
> ---
>  drivers/media/platform/qcom/venus/core.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/venus/core.c
> b/drivers/media/platform/qcom/venus/core.c
> index 30d4b9e..acf798c 100644
> --- a/drivers/media/platform/qcom/venus/core.c
> +++ b/drivers/media/platform/qcom/venus/core.c
> @@ -371,6 +371,14 @@ static int venus_remove(struct platform_device 
> *pdev)
>  	return ret;
>  }
> 
> +static void venus_core_shutdown(struct platform_device *pdev)
> +{
> +	int ret;
> +
> +	ret = venus_remove(pdev);
> +	WARN_ON(ret < 0);

I don't think you should warn here, its shutdown path and you can't
do anything with this WARN unlike remove callback where you have
to be sure to cleanup properly so that you are able to reload module.
But if you still want a hint about this failure, then just add a 
dev_err()
to indicate the failure instead of a big stack trace spamming kernel 
log.

Thanks,
Sai

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