linux-kernel - Re: [PATCH V4 2/4] iommu: of: Ignore all errors except EPROBE

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Date:   Thu, 18 May 2017 17:56:49 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Sricharan R <sricharan@...eaurora.org>
Cc:     robin.murphy@....com, will.deacon@....com, joro@...tes.org,
        lorenzo.pieralisi@....com, iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, m.szyprowski@...sung.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-acpi@...r.kernel.org, tn@...ihalf.com, hanjun.guo@...aro.org,
        okaya@...eaurora.org, robh+dt@...nel.org, frowand.list@...il.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        sudeep.holla@....com, rjw@...ysocki.net, lenb@...nel.org,
        catalin.marinas@....com, arnd@...db.de, linux-arch@...r.kernel.org,
        j.neuschaefer@....net, geert@...ux-m68k.org, magnus.damm@...il.com
Subject: Re: [PATCH V4 2/4] iommu: of: Ignore all errors except EPROBE_DEFER

Hi Sricharan,

Thank you for the patch.

On Thursday 18 May 2017 20:24:15 Sricharan R wrote:
> While deferring the probe of IOMMU masters, xlate and
> add_device callbacks called from of_iommu_configure
> can pass back error values like -ENODEV, which means
> the IOMMU cannot be connected with that master for real
> reasons. Before the IOMMU probe deferral, all such errors
> were ignored. Now all those errors are propagated back,
> killing the master's probe for such errors. Instead ignore
> all the errors except EPROBE_DEFER, which is the only one
> of concern and let the master work without IOMMU, thus
> restoring the old behavior.
> 
> Fixes: 7b07cbefb68d ("iommu: of: Handle IOMMU lookup failure with deferred
> probing or error") Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Tested-by: Magnus Damn <magnus.damn@...il.com>
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
> [V4] Reworded commit log and changed dev_info to dev_dbg
> 
>  drivers/iommu/of_iommu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index e6e9bec..19779b8 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -237,6 +237,12 @@ const struct iommu_ops *of_iommu_configure(struct
> device *dev, ops = ERR_PTR(err);
>  	}
> 
> +	/* Ignore all other errors apart from EPROBE_DEFER */
> +	if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) {
> +		dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops));
> +		ops = NULL;
> +	}
> +
>  	return ops;
>  }

-- 
Regards,

Laurent Pinchart