> -----Original Message-----
> From: [email protected] [mailto:iommu-
> [email protected]] On Behalf Of Will Deacon
> Sent: Wednesday, March 12, 2014 9:53 PM
> To: Sethi Varun-B16395
> Cc: [email protected]
> Subject: Re: [RFC][PATCH] iommu/arm: Add hotplugged devices support for
> arm-smmu.
> 
> Hi Varun,
> 
> On Sat, Mar 08, 2014 at 07:05:40PM +0000, Varun Sethi wrote:
> > Currently the ARM SMMU driver only considers the bus master devices in
> > the device tree. The master device and stream ID information is
> > maintained per SMMU. Currently there is no mechanism for representing
> > this information in case of PCI or hot plugged devices.
> >
> > This RFC patch proposes a mechanism for representing this information
> > for hot plugged/PCI devices.
> >
> > Patch doesn't contain the add_device callback modification for hot plug
> devices.
> > This would be bus specific and would be responsible for populating the
> > hot plug devices masters list for the SMMU.
> >
> > Signed-off-by: Varun Sethi <[email protected]>
> > ---
> >  drivers/iommu/arm-smmu.c |   93
> ++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 90 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
> > 1d9ab39..6c10df4 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -327,6 +327,9 @@ struct arm_smmu_master {
> >      * SMMU chain.
> >      */
> >     struct rb_node                  node;
> > +   /* Following fields correspond to the hot plug masters */
> > +   struct list_head                        hotplug_masters_node;
> > +   struct device                   *dev;
> 
> I'd much rather have one list for all masters. Distinguishing between
> masters and `hotplug masters' is unnecessary.
> 
> > +static int is_device_hotplug(struct device *dev) {
> > +   return (dev->bus != &platform_bus_type) &&
> > +            (dev->bus != &amba_bustype);
> > +}
> 
> I'm not fond of this. Why not rework what we currently have so that it
> can work for other (hotpluggable) buses?
> 
Ok, I will modify the code to use a list of masters per smmu.

-Varun
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