On 11/14/20 12:20 AM, Thierry Reding wrote: > On Mon, Oct 19, 2020 at 04:40:46PM -0500, Rob Herring wrote: >> On Fri, Oct 16, 2020 at 09:07:20PM +0800, JC Kuo wrote: >>> This commit describes the "nvidia,pmc" property for Tegra210 tegra-xusb >>> PHY driver. It is a phandle and specifier referring to the Tegra210 >>> pmc@7000e400 node. >>> >>> Signed-off-by: JC Kuo <jckuo@xxxxxxxxxx> >>> --- >>> v4: >>> new change to document "nvidia,pmc" prop >>> >>> .../devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt >>> index 38c5fa21f435..ea559baeb546 100644 >>> --- a/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt >>> +++ b/Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt >>> @@ -54,6 +54,7 @@ For Tegra210: >>> - avdd-pll-uerefe-supply: PLLE reference PLL power supply. Must supply 1.05 V. >>> - dvdd-pex-pll-supply: PCIe/USB3 PLL power supply. Must supply 1.05 V. >>> - hvdd-pex-pll-e-supply: High-voltage PLLE power supply. Must supply 1.8 V. >>> +- nvidia,pmc: phandle and specifier referring to the Tegra210 pmc@7000e400 node. >> >> 'Tegra210 pmc@7000e400' is kind of specific. Going to update this for >> every address and chip? >> >> If there's only one PMC, you can just find the compatible PMC node. Then >> you don't need a DT update. > > I did advise against doing the lookup by compatible string because I > think it has a couple of downsides. On one hand it's going to create an > additional maintenance burden on the XUSB pad controller driver because > the PMC is usually not compatible between SoC versions, so for every new > SoC generation we'll have to add the PMC compatible string to the XUSB > pad controller driver. > > On the other hand, this is new functionality and we can easily gate that > on the existence of this phandle, so it doesn't impact DT backwards > compatibility. That also has the advantage of explicitly listing the > dependency between the PMC and the XUSB pad controller in DT, so if we > ever do get around to come up with an even better mechanism to resolve > these dependencies than deferred probe, we do have the data already > available. > > Thierry > Hi Thierry, Thanks for the ideas. I will stay with the adding "nvidia,pmc" phandle property implementation. As for the DT document change, I will modify it with below. nvidia,pmc: phandle and specifier referring to the Tegra210 PMC node. Thanks, JC
