-----Original Message-----
From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi at arm.com]
Sent: Thursday, June 08, 2017 9:49 AM
To: Shameerali Kolothum Thodi
Cc: marc.zyngier at arm.com; sudeep.holla at arm.com; will.deacon at arm.com;
robin.murphy at arm.com; hanjun.guo at linaro.org; Gabriele Paoloni; John
Garry; iommu at lists.linux-foundation.org; linux-arm-
kernel at lists.infradead.org; linux-acpi at vger.kernel.org; devel at acpica.org;
Linuxarm; Wangzhou (B); Guohanjun (Hanjun Guo)
Subject: Re: [RFCv2 2/2] iommu/arm-smmu-v3:Enable ACPI based HiSilicon
erratum 161010801

On Tue, Jun 06, 2017 at 03:01:36PM +0000, Shameerali Kolothum Thodi
wrote:

[...]

quoted

quoted

quoted

+	irq_dom = pci_msi_get_device_domain(to_pci_dev(dev));
+	if (irq_dom) {
+		int	ret;
+		u32	rid;
+
+		rid = pci_msi_domain_get_msi_rid(irq_dom,

to_pci_dev(dev));

quoted

+		ret = iort_dev_find_its_base(dev, rid, 0, &base);

Well, here we use ITS id 0 which is fine as long as code in IORT
uses the same policy for getting the irq_domain (ie we want to
reserve the ITS address space that is actually used by the device to
send IRQs not a a different one) it is just a heads-up because I find this

confusing.

quoted

Ok. Just to make it clear, 0 is the index into the ITS identifier
list.  I noted that iort_get_device_domain() uses index 0 while
retrieving the ITS identifier.  May be use the same approach here as
well? ie, remove the index from function call?

I am not sure, how we can get the index info  though theoretically It
is possible for the ITS group node having multiple ITSs.

Actually I think it would make sense to reserve ALL ITS regions a device may
be mapped to instead of just index 0 (ie in your case it is equivalent); this
leaves us some leeway as to choose which ITS the device will be actually
mapped to and this code does not have to care.

Ok. That make sense. Just a quick one, is it ok to add another helper function in
iort code to retrieve the its->its_count then? 

Thanks,
Shameer