On Mon, May 9, 2016 at 1:25 PM, Stefan Agner <stefan@xxxxxxxx> wrote: > On 2016-05-09 10:14, Rob Herring wrote: >> On Thu, May 5, 2016 at 3:27 AM, <maitysanchayan@xxxxxxxxx> wrote: >>> Hello Rob, >>> >>> On 16-05-03 21:30:26, Rob Herring wrote: >>>> On Mon, May 02, 2016 at 12:35:04PM +0530, Sanchayan Maity wrote: >>>> > Add device tree binding documentation for Vybrid SoC. >>>> > >>>> > Signed-off-by: Sanchayan Maity <maitysanchayan@xxxxxxxxx> >>>> > --- >>>> > .../bindings/arm/freescale/fsl,vf610-soc.txt | 35 ++++++++++++++++++++++ >>>> > 1 file changed, 35 insertions(+) >>>> > create mode 100644 Documentation/devicetree/bindings/arm/freescale/fsl,vf610-soc.txt >>>> > >>>> > diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,vf610-soc.txt b/Documentation/devicetree/bindings/arm/freescale/fsl,vf610-soc.txt >>>> > new file mode 100644 >>>> > index 0000000..bdd95e8 >>>> > --- /dev/null >>>> > +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,vf610-soc.txt >>>> > @@ -0,0 +1,35 @@ >>>> > +Vybrid System-on-Chip >>>> > +--------------------- >>>> > + >>>> > +Required properties: >>>> > + >>>> > +- #address-cells: must be 1 >>>> > +- #size-cells: must be 1 >>>> > +- compatible: "fsl,vf610-soc-bus", "simple-bus" >>>> >>>> If this is a bus, put the file in bindings/bus/... >>> >>> The fsl,vf610-soc-bus binding is used to bind the driver in question with >>> an appropriate compatible node. >>> >>> Basically being a standalone platform driver, there was need of a compatible >>> property to bind on. Introducing a separate device tree node for it's sake >>> didn't seem appropriate so the alteration to SoC node's compatible. >> >> Ah, so you are designing a node around the needs of a Linux specific >> driver. Don't do that. DT describes the h/w and this node is not a h/w >> block. >> >> Create a platform device based on a matching SOC compatible string >> instead and make your driver find the information it needs directly >> from the relevant nodes like the ROM node. > > That reads like my words a year ago: > https://lkml.org/lkml/2015/5/22/408 > > Initially pretty much everything was hard-coded in the driver. > > Arnd then pushed to use more descriptive in the device tree. > > Of course, we should not end up making up relations which are not there > in hardware. We need to find the right balance. > > Here is my suggestion: > 1. Add "fsl,vf610-soc-bus" as compatible string to the soc node, use it > to bind the "soc bus driver" as a platform driver located in driver/soc/ I'm not convinced this is a h/w block. This keeps coming up and I think this is a kernel problem, not a DT problem. Let's face it that there are drivers at the SOC level which don't fit into a DT node. They may be the exception, but they are a common exception. My proposal for how to deal with these cases is here[1]. I also think drivers/soc is a mess because it is randomly used or not. IMO, using it should not be at the whim of whomever does SOC support. > 2. Add ROM as syscon device (it is not erasable ROM memory, hence eeprom > seems not to be appropriate) It is not a syscon. It is just memory. nvmem covers read-only memory, so I have no issue using that. Rob [1] https://lkml.org/lkml/2013/10/30/27 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
