On Fri, Sep 22, 2023 at 10:57:36AM +0100, Conor Dooley wrote: > Hey Drew, > > On Thu, Sep 21, 2023 at 06:49:48PM -0700, Drew Fustini wrote: > > Add compatible value for the T-Head TH1520 dwcmshc controller and add > > thead,phy-pull-up property. > > > > Signed-off-by: Drew Fustini <dfustini@xxxxxxxxxxxx> > > --- > > Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml > > index a43eb837f8da..46b768d46712 100644 > > --- a/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml > > +++ b/Documentation/devicetree/bindings/mmc/snps,dwcmshc-sdhci.yaml > > @@ -19,6 +19,7 @@ properties: > > - rockchip,rk3568-dwcmshc > > - rockchip,rk3588-dwcmshc > > - snps,dwcmshc-sdhci > > + - thead,th1520-dwcmshc > > > > reg: > > maxItems: 1 > > @@ -60,6 +61,9 @@ properties: > > description: Specify the number of delay for tx sampling. > > $ref: /schemas/types.yaml#/definitions/uint8 > > > > + thead,phy-pull-up: > > + description: Enable weak pull-up on PHY pads > > + type: boolean > > Why is the weak pull-up required? How would the dts author know if they > need to use this property? This is a good question, and I don't have a good reason beyond it is what the vendor SDK was doing. There are only two boards right now using the TH1520 that I know of. Both the LPi4a [1] and the Ahead [2] have the pull-up property set on all the mmc controller nodes their downstream device trees. Rob suggested on #devicetree that it would be simpler to just enable it in the driver and disable support when needed. I like this idea as it will simplify this binding patch and the code in the driver patch. Thanks, Drew [1] https://git.beagleboard.org/beaglev-ahead/BeagleBoard-DeviceTrees/-/blob/v5.10.x-ti-unified/src/riscv/light-beagle-ref.dts [2] https://github.com/revyos/thead-kernel/blob/lpi4a/arch/riscv/boot/dts/thead/light-lpi4a-ref.dts
