Mention clkbuf_inhibit can be overridden

This commit is contained in:
Eddie Hung 2019-08-23 10:24:59 -07:00
parent 4d89c3f468
commit 4c0404ae02
1 changed files with 8 additions and 7 deletions

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@ -332,17 +332,18 @@ Verilog Attributes and non-standard features
that represent module parameters or localparams (when the HDL front-end
is run in -pwires mode).
- The ``clkbuf_inhibit`` attribute can be set on a wire to prevent
automatic clock buffer insertion by ``clkbufmap``.
- The ``clkbuf_sink`` attribute can be set on an input port of a blackbox
module to request clock buffer insertion by the ``clkbufmap`` pass.
- The ``clkbuf_driver`` attribute can be set on an output port of a blackbox
module to mark it as a clock buffer output, and thus prevent ``clkbufmap``
from inserting another clock buffer on a net driven by such output.
- The ``iopad_external_pin`` attribute on a blacbox module's port marks
- The ``clkbuf_sink`` attribute can be set on an input port of a module to
request clock buffer insertion by the ``clkbufmap`` pass.
- The ``clkbuf_inhibit`` is the default attribute to set on a wire to prevent
automatic clock buffer insertion by ``clkbufmap``. This behaviour can be
overridden by providing a custom selection to ``clkbufmap``.
- The ``iopad_external_pin`` attribute on a blackbox module's port marks
it as the external-facing pin of an I/O pad, and prevents ``iopadmap``
from inserting another pad cell on it.