Hi Ulf, hi Rob > Ulf Hansson <ulf.hansson@xxxxxxxxxx> hat am 30. August 2016 um 11:26 > geschrieben: > > > On 18 August 2016 at 14:25, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > > On 11/08/16 03:48, Shawn Lin wrote: > >> + Adrian > >> > >> Let's queue Adrian here who now maintains SDHCI stuff. > > > > SDHCI drivers may not implement no-1-8-v in a consistent manner, but as far > > as I can see, the meaning is still clear: 1.8V will not be used for either > > supply or signaling. > > Okay. > > > > > SDHCI is complicated because the SDHCI specification does not cover eMMC. > > From the perspective of SDHCI, the only 1.8V modes are the UHS-I modes, so > > support for 1.8V signaling is the same as support for one of those modes > > (the spec even says as much). But what happens is that the host controller > > can support those modes but the board can't supply 1.8V so the drivers > > remove capability for the modes. Support for 1.8V supply has a capability > > bit which drivers can override if necessary but removable SD cards don't > > support 1.8V supply anyway, so the issue doesn't arise if the host > > controller is only used for uSD cards. > > By looking how SDHCI uses the SDHCI_SUPPORT_DDR50 in conjunction with > SDHCI_QUIRK2_NO_1_8_V (which is set when no-1-8-v DT property is > provided), this becomes a bit messy. > > From Adrian's summary above, it then seems appropriate to limit the > no-1-8-v DT property to apply only to capabilities related to SD > cards, as I assume that also was the original purpose. > > Do you think it's possible to clean up this in sdhci when assigning > the caps masks, and then also clarify the no-1-8-v DT binding in the > documentation? was the question addressed to me? I think this clean up should be a separate patch series. Unfortunately i don't have a clue about what exactly and how it should be fixed. > > Regarding the new DT binding proposed to be added, mmc-ddr-3_3v, it > seems we need this to be able to properly describe the HW. > Rob, do you have an issue with adding this binding? I am thinking that > we already have mmc-ddr-1_8v and mmc-ddr-1_2v, so it just follow > existing pattern. @Rob: gently ping ... Regards Stefan > > [...] > > Kind regards > Uffe > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- 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
