linux-kernel - Re: [PATCH v6 05/07] iommu/ipmmu-vmsa: Add new IOMMU_DOMAIN

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Date:   Fri, 11 Nov 2016 03:13:32 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Robin Murphy <robin.murphy@....com>,
        Magnus Damm <magnus.damm@...il.com>,
        iommu@...ts.linux-foundation.org,
        laurent.pinchart+renesas@...asonboard.com, geert+renesas@...der.be,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        horms+renesas@...ge.net.au, m.szyprowski@...sung.com
Subject: Re: [PATCH v6 05/07] iommu/ipmmu-vmsa: Add new IOMMU_DOMAIN_DMA ops

Hello,

On Thursday 10 Nov 2016 12:42:06 Joerg Roedel wrote:
> On Fri, Oct 21, 2016 at 06:52:53PM +0100, Robin Murphy wrote:
> > > -static struct iommu_domain *ipmmu_domain_alloc(unsigned type)
> > > -{
> > > -	if (type != IOMMU_DOMAIN_UNMANAGED)
> > > -		return NULL;
> > 
> > I *think* that if we did the initial check thus:
> > 	if (type != IOMMU_DOMAIN_UNMANAGED ||
> > 	
> > 	    (IS_ENABLED(CONFIG_IOMMU_DMA) && type != IOMMU_DOMAIN_DMA))
> > 		
> > 		return NULL;
> > 
> > it shouldn't be necessary to split the function at all - we then just
> > wrap the {get,put}_cookie() bits in "if (type ==  IOMMU_DOMAIN_DMA)" and
> > in the 32-bit ARM case they just don't run as that can never be true.
> 
> This would be a good improvement. Magnus, Robin, can either of you send
> a follow-on patch to implement this suggestion? I have applied these
> patches to my arm/renesas branch (not pushed yet). The patch can be
> based on it.

I like the suggestion too, a patch is on its way.

Joerg, as I've sent a few comments about the other patches (sorry for the late 
review, I got delayed by KS and LPC), the follow-up patch should probably be 
squashed into this one when Magnus addresses my comments. Could you please 
hold off pushing the arm/renesas branch until Magnus replies to this ?

-- 
Regards,

Laurent Pinchart