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Date: Thu, 12 Dec 2013 18:14:02 -0800
From: Greg KH <gregkh@linuxfoundation.org>
To: Grant Likely <grant.likely@linaro.org>
Cc: Hiroshi Doyu <hdoyu@nvidia.com>, Stephen Warren <swarren@wwwdotorg.org>,
        swarren@nvidia.com, will.deacon@arm.com, thierry.reding@gmail.com,
        robherring2@gmail.com, joro@8bytes.org, mark.rutland@arm.com,
        devicetree@vger.kernel.org, lorenzo.pieralisi@arm.com,
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        galak@codeaurora.org, linux-tegra@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv7 04/12] driver/core: populate devices in order for IOMMUs
Message-ID: <20131213021402.GB14192@kroah.com>
References: <1386835033-4701-1-git-send-email-hdoyu@nvidia.com>
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 <20131212113920.70E8BC40637@trevor.secretlab.ca>
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On Thu, Dec 12, 2013 at 11:39:20AM +0000, Grant Likely wrote:
> On Thu, 12 Dec 2013 09:57:05 +0200, Hiroshi Doyu <hdoyu@nvidia.com> wrote:
> > IOMMU devices on the bus need to be poplulated first, then iommu
> > master devices are done later.
> > 
> > With CONFIG_OF_IOMMU, "iommus=" DT binding would be used to identify
> > whether a device can be an iommu msater or not. If a device can, we'll
> > defer to populate that device till an iommu device is populated. Then,
> > those deferred iommu master devices are populated and configured with
> > help of the already populated iommu device.
> > 
> > Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> > This is related to the following discussion:
> >   [RFC PATCH] Documentation: devicetree: add description for generic bus properties
> >   http://lists.infradead.org/pipermail/linux-arm-kernel/2013-November/215042.html
> > 
> > v6:
> > Spinned off only driver core part from:
> >   [PATCHv5 2/9] driver/core: populate devices in order for IOMMUs
> > 
> > v5:
> > Use "iommus=" binding instread of arm,smmu's "#stream-id-cells".
> > 
> > v4:
> > This is newly added, and the successor of the following RFC:
> >   [RFC][PATCHv3+ 1/2] driver/core: Add of_iommu_attach()
> >   http://lists.linuxfoundation.org/pipermail/iommu/2013-November/006914.html
> > 
> > Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
> > ---
> >  drivers/base/dd.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> > index 0605176..0605f52 100644
> > --- a/drivers/base/dd.c
> > +++ b/drivers/base/dd.c
> > @@ -25,6 +25,7 @@
> >  #include <linux/async.h>
> >  #include <linux/pm_runtime.h>
> >  #include <linux/pinctrl/devinfo.h>
> > +#include <linux/of_iommu.h>
> >  
> >  #include "base.h"
> >  #include "power/power.h"
> > @@ -273,6 +274,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> >  
> >  	dev->driver = drv;
> >  
> > +	ret = of_iommu_attach(dev);
> > +	if (ret)
> > +		goto probe_failed;
> > +
> 
> As discussed before, I really don't think hooking in to dd.c is the
> right thing to do here, and certainly not as a device tree specific
> function. ACPI or PCI described devices may have the same constraints
> and those won't have DT descriptions.

I agree, this shouldn't be in the driver core.

greg k-h