Hi Rob. 2016-12-13 2:14 GMT+09:00 Rob Herring <robh@xxxxxxxxxx>: >> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt >> new file mode 100644 >> index 0000000..750374f >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt >> @@ -0,0 +1,30 @@ >> +* Cadence SD/SDIO/eMMC Host Controller >> + >> +Required properties: >> +- compatible: should be "cdns,sd4hc". > > Needs SoC specific compatible strings too. I remember you mentioned the vendor prefix stands for the SoC vendor, not the IP vendor. The compatible prefixed with the IP vendor is prepared for a fallback. I will add "socionext,sd4hc". >> +- reg: offset and length of the register set for the device. >> +- interrupts: a single interrupt specifier. >> +- clocks: phandle to the input clock. >> + >> +Optional properties: >> +For eMMC configuration, supported speed modes are not indicated by the SDHCI >> +Capabilities Register. Instead, the following properties should be specified >> +if supported. See mmc.txt for details. >> +- mmc-ddr-1_8v >> +- mmc-ddr-1_2v >> +- mmc-hs200-1_8v >> +- mmc-hs200-1_2v >> +- mmc-hs400-1_8v >> +- mmc-hs400-1_2v > > There's now a property to override SDHCI capabilities register. Maybe > you should use that instead? I'll defer to Ulf. > I did not know this new property. So, now we have two ways to specify MMC speed mode capabilities by only touching DT. [1] Add MMC mode flags directly, like I did. [2] Use "sdhci-caps-mask" and "sdhci-caps" The problem for [2] is that eMMC capabilities do not perfectly correspond to the SDHCI capabilities register. >> +- mmc-hs400-1_8v >> +- mmc-hs400-1_2v If the driver sets SDHCI_QUIRK2_CAPS_BIT63_FOR_HS400, we can use the bit63 of caps for specifying HS400. But, this is not defined in the SDHCI standard. #define SDHCI_SUPPORT_HS400 0x80000000 /* Non-standard */ >> +- mmc-ddr-1_8v For High Speed DDR, perhaps we can imply MMC_CAP_1_8V_DDR from MMC_CAP_UHS_DDR50 (bit34 of caps) This is not supported in the current code, but if this is a good idea, I can send a patch. >> +- mmc-ddr-1_2v This does not have the corresponding bit, but 1.2V is not commonly used, so this is not a fatal problem. What I can do at most now, is to delete the Optional properties section entirely so users can choose [1] or [2] as they like. -- Best Regards Masahiro Yamada -- 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
