lkml.org 
[lkml]   [2020]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev
    On Wed, Sep 30, 2020 at 06:36:52PM +0300, Dmitry Osipenko wrote:
    > I'...
    > >> + struct tegra_mc *mc = devm_tegra_get_memory_controller(dev);
    > >> + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
    > >
    > > It looks to me like the only reason why you need this new global API is
    > > because PCI devices may not have a device tree node with a phandle to
    > > the IOMMU. However, SMMU support for PCI will only be enabled if the
    > > root complex has an iommus property, right? In that case, can't we
    > > simply do something like this:
    > >
    > > if (dev_is_pci(dev))
    > > np = find_host_bridge(dev)->of_node;
    > > else
    > > np = dev->of_node;
    > >
    > > ? I'm not sure exactly what find_host_bridge() is called, but I'm pretty
    > > sure that exists.
    > >
    > > Once we have that we can still iterate over the iommus property and do
    > > not need to rely on this global variable.
    >
    > This sounds more complicated than the current variant.

    I don't think so. It's actually very clear and explicit. And yes, this
    might be a little more work (and honestly, this is what? a handful of
    lines?) than accessing a global variable, but that's a fair price to pay
    for proper encapsulation.

    > Secondly, I'm already about to use the new tegra_get_memory_controller()
    > API for all the T20/30/124/210 EMC and devfreq drivers.

    Also, this really proves the point I was trying to make about how this
    is going to proliferate...

    Thierry
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2020-09-30 18:11    [W:2.826 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site