On Sat, Sep 23, 2023 at 04:10:11PM +0800, Guo Ren wrote: > On Fri, Sep 22, 2023 at 11:18 PM Drew Fustini <dfustini@xxxxxxxxxxxx> wrote: > > > > 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. > It's for the PHY debug. You could directly remove them, or keep it > with no-pull-up flag, then no pull-up flag in the dts for default.. Thank you for explaining that the purpose of the pull-up DT property was for PHY debug. I will plan to remove the pull-up DT property in the next version of this patch series and remove sdhci_phy_1_8v_init_no_pull() and sdhci_phy_3_3v_init_no_pull() from my sdhci-of-dwcmshc.c patch. I will make th1520_phy_1_8v_init() and th1520_phy_3_3v_init() always set WEAKPULL_EN = 1 (PULLUP) for CMDPAD_CNFG, DATAPAD_CNFG, RSTNPAD_CNFG and set WEAKPULL_EN = 2 (PULLDOWN) for STBPAD_CNFG. Thanks, Drew
