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Date:   Fri, 4 Jun 2021 09:51:29 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Kai Ye <yekai13@huawei.com>
Cc:     linux-accelerators@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        linuxarm@huawei.com, zhangfei.gao@linaro.org,
        wangzhou1@hisilicon.com
Subject: Re: [PATCH] uacce: add print information if not enable sva
Message-ID: <YLnbgcJmQZChx1WV@kroah.com>
References: <1622792769-28017-1-git-send-email-yekai13@huawei.com>
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On Fri, Jun 04, 2021 at 03:46:09PM +0800, Kai Ye wrote:
> Add print information necessary if user not enable sva.
> 
> Signed-off-by: Kai Ye <yekai13@huawei.com>
> ---
>  drivers/misc/uacce/uacce.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index bae18ef0..fe38af8 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -387,15 +387,22 @@ static void uacce_release(struct device *dev)
>  
>  static unsigned int uacce_enable_sva(struct device *parent, unsigned int flags)
>  {
> +	int ret;
> +
>  	if (!(flags & UACCE_DEV_SVA))
>  		return flags;
>  
>  	flags &= ~UACCE_DEV_SVA;
>  
> -	if (iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_IOPF))
> +	ret = iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_IOPF);
> +	if (ret) {
> +		dev_err(parent, "failed to enable IOPF feature! ret = %d\n", ret);

Why is this needed?  Has this ever happened in real life such that the
log message is now required?


>  		return flags;
> +	}
>  
> -	if (iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_SVA)) {
> +	ret = iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_SVA);
> +	if (ret) {
> +		dev_err(parent, "failed to enable SVA feature! ret = %d\n", ret);

Same here, does this happen in real systems?

thanks,

greg k-h