linux-kernel - Re: [PATCH v2 06/11] iommu/ipmmu-vmsa: Teach xlate() to skip disabled iommus

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Date:	Wed, 08 Jun 2016 03:23:54 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	iommu@...ts.linux-foundation.org,
	laurent.pinchart+renesas@...asonboard.com, geert+renesas@...der.be,
	joro@...tes.org, linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org, horms+renesas@...ge.net.au
Subject: Re: [PATCH v2 06/11] iommu/ipmmu-vmsa: Teach xlate() to skip disabled iommus

Hi Magnus,

Thank you for the patch.

I agree with the comment that Geert made on v1, and I haven't seen you 
replying to it or addressing it.

Quoting Geert,

"I think this should be handled in drivers/iommu/of_iommu.c:of_iommu_init()
instead, cfr. commit 3e5dd6f6e690048d ("clk: Ignore disabled DT clock
providers")."

On Monday 06 Jun 2016 12:58:22 Magnus Damm wrote:
> From: Magnus Damm <damm+renesas@...nsource.se>
> 
> The ->xlate() call gets invoked even though the iommu
> device has status = "disabled" in DT, so make sure we
> skip over disabled devices.
> 
> In my mind it would make sense to have this at some
> shared level, but I guess some users may want to
> configure the iommu regardless of DT state.
> 
> Signed-off-by: Magnus Damm <damm+renesas@...nsource.se>
> ---
> 
>  Changes since V1:
>  - Reworked slightly to fit on top of updated patch order
> 
>  drivers/iommu/ipmmu-vmsa.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> --- 0017/drivers/iommu/ipmmu-vmsa.c
> +++ work/drivers/iommu/ipmmu-vmsa.c	2016-06-06 10:58:18.530607110 +0900
> @@ -1001,7 +1001,13 @@ static struct iommu_group *ipmmu_device_
>  static int ipmmu_of_xlate_dma(struct device *dev,
>  			      struct of_phandle_args *spec)
>  {
> -	/* dummy callback to satisfy of_iommu_configure() */
> +	/* If the IPMMU device is disabled in DT then return error
> +	 * to make sure the of_iommu code does not install ops
> +	 * even though the iommu device is disabled
> +	 */
> +	if (!of_device_is_available(spec->np))
> +		return -ENODEV;
> +
>  	return 0;
>  }

-- 
Regards,

Laurent Pinchart