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Re: [PATCH v12 3/6] fpga: add simple-fpga-bus

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On Wed, Oct 28, 2015 at 08:37:51AM -0700, Moritz Fischer wrote:
> On Wed, Oct 28, 2015 at 3:07 AM, Josh Cartwright <joshc@ni.com> wrote:
> > On Tue, Oct 27, 2015 at 05:09:12PM -0500, atull@opensource.altera.com wrote:
> >> From: Alan Tull <atull@opensource.altera.com>
> >>
> >> The Simple FPGA bus uses the FPGA Manager Framework and the
> >> FPGA Bridge Framework to provide a manufactorer-agnostic
> >> interface for reprogramming FPGAs that is Device Tree
> >> Overlays-based.
> >
> > Do you intend the "simple-fpga-bus" to be used on Zynq as well?  The
> > whole concept of the socfpga's "FPGA Bridge" doesn't map to the Zynq at
> > all, from what I can tell.
> 
> For Zynq the zynq-fpga driver takes care of the level shifters on full
> reconfiguration,
> and doesn't for partial reconfiguration. Now depending on which parts
> of the fabric
> are partial reconfigured (say AXI masters), one might run into issues
> with a setup like that.
> 
> My first plan was to counter that by using zynq-reset to hold the
> reset high during
> reconfiguration of that part of the FPGA.
> 
> I'm happy to rethink that part and maybe redo the level shifters and
> resets together in a bridge
> driver under devicetree control gives finer grained control.

There is already a framework which is used to describe and manipulate
level shifting/other IO properties, and that is pinctrl, and if we
wanted to use an appropriate abstraction, I think pinctrl would be the
best bet.

Implementing the FPGA Bridge interface in the Zynq driver because it's
what the core expects is just backwards.  It's an abstraction inversion.

  Josh
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Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Josh Cartwright <joshc@ni.com> - 2015-10-28 11:10 +0100
  Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Moritz Fischer <moritz.fischer@ettus.com> - 2015-10-28 16:40 +0100
    Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Josh Cartwright <joshc@ni.com> - 2015-10-28 17:20 +0100
      Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Moritz Fischer <moritz.fischer@ettus.com> - 2015-10-28 17:30 +0100
        Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Josh Cartwright <joshc@ni.com> - 2015-10-28 19:00 +0100
          Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Josh Cartwright <joshc@ni.com> - 2015-10-28 19:10 +0100
          Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Moritz Fischer <moritz.fischer@ettus.com> - 2015-10-28 21:40 +0100
      Re: [PATCH v12 3/6] fpga: add simple-fpga-bus Rob Herring <robh+dt@kernel.org> - 2015-10-29 05:10 +0100

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