[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH V3 5/8] iommu/arm: Add lightweight iommu_fwspec support



Hi Oleksandr,

On 8/20/19 7:09 PM, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

We need to have some abstract way to add new device to the IOMMU
based on the generic IOMMU DT bindings [1] which can be used for
both DT (right now) and ACPI (in future).

For that reason we can borrow the idea used in Linux these days
called "iommu_fwspec". Having this in, it will be possible
to configure IOMMU master interfaces of the device (device IDs)
from a single common place and avoid keeping almost identical look-up
implementations in each IOMMU driver.

There is no need to port the whole implementation of "iommu_fwspec"
to Xen, we could, probably, end up with a much simpler solution,
some "stripped down" version which fits our requirements.

So, this patch adds the following:
1. A common structure "iommu_fwspec" to hold the the per-device
    firmware data
2. New member "iommu_fwspec" of struct device
3. Functions/helpers to deal with "dev->iommu_fwspec"

It should be noted that in comparing with original "iommu_fwspec"

s/comparing with/comparison of/
s/original/the Linux/ or "the original".

Xen's variant doesn't contain some fields, which are not really
needed at the moment (ops, flag) and "iommu_fwnode" field was replaced
by "iommu_dev" to avoid porting a lot of code (to support "fwnode_handle")
with little benefit.


It would be good to mention which version of Linux this is based on. So if there is a critical bug in Linux we can port it.

The rest of the patch looks good to me.

Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.