[...] >>> + >>> +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. Let me clarify a bit. The point with the new bindings is to be able to override *broken* SDHCI caps bits. So, not only related to the speed modes. > > [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. > I think a better approach is to use the new sdhci-caps* bindings to mask those caps that can't be trusted. And then use the generic mmc bindings for speed modes instead. That should be a safer approach, right!? Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
