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There's an optimisation in the PE setup which skips performing DMA setup for a PE if we only have bridges in a PE. The assumption being that only "real" devices will DMA to system memory, which is probably fair. However, if we start off with only bridge devices in a PE then add a non-bridge device the new device won't be able to use DMA because we never configured it. Fix this (admittedly pretty weird) edge case by tracking whether we've done the DMA setup for the PE or not. If a non-bridge device is added to the PE (via rescan or hotplug, or whatever) we can set up DMA on demand. This also means the only remaining user of the old "DMA Weight" code is the IODA1 DMA setup code that it was originally added for, which is good. Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200722065715.1432738-3-oohall@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.