Hi, On Tuesday 26 December 2017 11:40 PM, Tony Lindgren wrote: > * Rob Herring <robh@xxxxxxxxxx> [171226 17:49]: >> On Fri, Dec 22, 2017 at 12:24 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: >>> * Kishon Vijay Abraham I <kishon@xxxxxx> [171222 06:06]: >>>> Hi Rob, >>>> >>>> On Thursday 21 December 2017 12:27 AM, Rob Herring wrote: >>>>> On Tue, Dec 19, 2017 at 02:28:22PM +0530, Kishon Vijay Abraham I wrote: >>>>>> Add syscon properties required for configuring PCIe in x2 lane mode. >>>>>> >>>>>> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> >>>>>> Signed-off-by: Sekhar Nori <nsekhar@xxxxxx> >>>>>> --- >>>>>> Documentation/devicetree/bindings/pci/ti-pci.txt | 6 ++++++ >>>>>> 1 file changed, 6 insertions(+) >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/pci/ti-pci.txt b/Documentation/devicetree/bindings/pci/ti-pci.txt >>>>>> index 82cb875e4cec..bfbc77ac7355 100644 >>>>>> --- a/Documentation/devicetree/bindings/pci/ti-pci.txt >>>>>> +++ b/Documentation/devicetree/bindings/pci/ti-pci.txt >>>>>> @@ -13,6 +13,12 @@ PCIe DesignWare Controller >>>>>> - ti,hwmods : Name of the hwmod associated to the pcie, "pcie<X>", >>>>>> where <X> is the instance number of the pcie from the HW spec. >>>>>> - num-lanes as specified in ../designware-pcie.txt >>>>>> + - ti,syscon-lane-conf : phandle/offset pair. Phandle to the system control >>>>>> + module and the register offset to specify 1 lane or >>>>>> + 2 lane. >>>>>> + - ti,syscon-lane-sel : phandle/offset pair. Phandle to the system control >>>>>> + module and the register offset to specify lane >>>>>> + selection. >>>>> >>>>> Adding a property for every syscon register doesn't really scale and >>>>> doesn't work if the register layout changes. >>>> >>>> The register layout doesn't really change between silicon revisions and for new >>>> SoCs, the phandle and the register offset for that SoC will have to be >>>> populated again. >> >> And what about SoCs that don't exist yet? >> >>>> Having said that, I'm not aware of any other alternative here. >> >> What would you do if you had 20 different syscon registers to >> configure? Add 20 properties? No, you would have per SoC functions in >> the driver to handle the different cases. > > Ideally these syscon registers would be managed by some Linux > generic framework such as clock/regulator/mux/phy. > > But yeah, if that does not work, then setting a SoC specific > configuration function based on the compatible value makes sense > to me. All right. I'll add a function for syscon configuration in pci-dra7xx. Thanks Kishon
