Improve ipbus drp bridge

[jhegeman]

The original implementation of the ipbus_drp_bridge did not allow for a DRP clock different from the IPBus clock. This new implementation does. A generic allows one to choose at implementation time whether or not to include an IPBus clock bridge. The default values for the generic and the new DRP clock input port should ensure that this is fully backwards-compatible.

[tswilliams]

Hi @jhegeman

Thanks for these changes. They look good to me, just one minor comment: I spotted that stb2_d - and hence also stb2 - is ultimately not used. I just wanted to check that this isn't an indication that you'd forgotten to push some additional logic which uses those signals.

[jhegeman]

Hi @tswilliams,

Well spotted! These are left-overs from an intermediate implementation, in which they were used to tweak the busy signal. I have removed them now.

Cheers, Jeroen

[tswilliams]

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