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When a GSI channel is initially allocated, and after it has been reset, the hardware assumes its ring index is 0. And although we do initialize channels this way, the comments in the IPA code don't really explain this. For event rings, it doesn't matter what value we use initially, so using 0 is just fine. Add some information about the assumptions made by hardware above the definition of the gsi_ring structure in "gsi.h". Zero the index field for all rings (channel and event) when the ring is allocated. As a result, that function initializes all fields in the structure. Stop zeroing the index the top of gsi_channel_program(). Initially we'll use the index value set when the channel ring was allocated. And we'll explicitly zero the index value in gsi_channel_reset() before programming the hardware, adding a comment explaining why it's required. For event rings, use the index initialized by gsi_ring_alloc() rather than 0 when ringing the doorbell in gsi_evt_ring_program(). (It'll still be zero, but we won't assume that to be the case.) Use a local variable in gsi_evt_ring_program() that represents the address of the event ring's ring structure. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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.