On Tue, Apr 8, 2014 at 1:52 PM, Rob Herring <robherring2@xxxxxxxxx> wrote: > On Tue, Apr 8, 2014 at 11:02 AM, delicious quinoa > <delicious.quinoa@xxxxxxxxx> wrote: >> On Tue, Apr 8, 2014 at 9:33 AM, Steffen Trumtrar >> <s.trumtrar@xxxxxxxxxxxxxx> wrote: >>> On Tue, Apr 08, 2014 at 09:29:50AM -0500, Thor Thayer wrote: >>>> On Tue, 2014-04-08 at 15:38 +0200, Steffen Trumtrar wrote: >>>> > Hi! >>>> > >>>> > On Mon, Apr 07, 2014 at 04:54:07PM -0500, tthayer@xxxxxxxxxx wrote: >>>> > > From: Thor Thayer <tthayer@xxxxxxxxxx> >>>> > > >>>> > > Addition of the Altera SDRAM controller bindings and device >>>> > > tree changes to the Altera SoC project. >>>> > > >>>> [snip] >>>> > > + >>>> > > +Required properties: >>>> > > +- compatible : "altr,sdr-ctl", "syscon"; >>>> > > + Note that syscon is invoked for this device to support the FPGA >>>> > > + bridge driver, EDAC driver and other devices that share the >>>> > > + registers. >>>> > > +- reg : Should contain 1 register ranges(address and length) >>>> > >>>> > I haven't really thought this through, but why would the FPGA bridge driver >>>> > access the sdram controller? For releasing the resets in fpgaportrst ? Or is >>>> > there more? >>>> >>>> Hi Steffan. No, not for resets. We need to enable the FPGA to SDRAM >>>> path. Our SDRAM controller allows FPGA master access to the SDRAM. >>>> >>> >>> Yes. But what you have to do to enable the path is let the FPGA port you use >>> out of reset. And that is it as far as I can see. The rest happens in the >>> bitstream. Or is there more to enable the path? >>> The FPGA2SDRAM bridge is the one I didn't use as of yet, so if I miss something >>> please elaborate. >> >> Hi Steffen, >> >> The sdram controller is used by two drivers. That's why we want to >> specify "syscon" here. The other driver is the FPGA bridge driver. >> Its functionality is very separate from what this driver is doing (we >> are not enabling the bridge in this driver; we are enabling the >> monitoring and resetting the interrupt bit of the EDAC). We wanted to >> specify "syscon" her so that we don't have to have to change it for >> the other driver. > > But are there actually overlapping registers which are accessed by > both drivers and need the protection of regmap? No overlapping registers here. Just various registers that are used by: edac driver, fpga bridge, low power modes. So no special protection needed. > > Perhaps MFD is more appropriate than syscon? > > Rob A syscon will do fine here. If we did a MFD, all it would be doing would be providing register access for this range of registers to a few drivers, so syscon does that without any trouble. Alan Tull aka delicious quinoa -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
