Hi Doug/ Krzysztof , On 15 October 2015 at 04:10, Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > Hi, > > On Tue, Oct 13, 2015 at 6:06 PM, Alim Akhtar <alim.akhtar@xxxxxxxxx> wrote: >> +Doug >> Hello, >> AFAIR, dw_mmc host controller does support UHS-I [1], specially SDR50 >> and SDR104 modes. >> >> [1]: http://www.spinics.net/lists/linux-mmc/msg28186.html >> >> What I remember is, one need to set "broken-cd" property also in order >> to make it work because of the vqmmc and vmmc connection on board. I >> didn't find the link right now, but you can search on the web, there >> was a long discussion about handling this. >> Have not checked it recently, so not sure if this got broken somehow. > > Right. It _shouldn't_ be possible to add "vmmc/vqmmc" supplies to > your DTS (which you do in patch 2/3) and also to use the "gpc2-2" pin > for card detect (even if you configure it as a GPIO). Once you add > "vmmc/vqmmc" then Linux ought to be turning these regulators off when > no card is plugged in. Presumably the "vqmmc" regulator is hooked up > to the "VDDQ_MMC2". If you look in the user manual for 5422 you can > see that "GPC2[2]/SD_2_CDn" has power domain "VDDQ_MMC2". Thus you > really shouldn't be using that pin when vqmmc is off. I think at some > point someone claimed that it still worked for them, but nobody could > ever explain why. Full discussion at > <https://patchwork.kernel.org/patch/4763881/> > > --- > > In case it matters, comments on stuff from earlier in the thread: > > * As people pointed out, exynos5422 certainly supports all these modes > (including DDR50) in the SoC. > > * Just because the SoC supports these modes doesn't mean that the > boards do, which is why the SoC .dtsi doesn't include them. Thus, > this patch is "right" in that it changes a board-specific file. > > * As Krzysztof points out this board doesn't "add" support but rather > "enables" support. The distinction is subtle. > > * You might be able to get DDR50 working, but probably better to just > start with SDR modes. Previously I never attempted to get DDR50 cards > working, so possibly the software needs extra work? > Thanks for clarifying all the background details on the mmc changes. Here is what I would conclude from the previous mail chain's. 1 Drop the cd-gpios changes. pinctrl-0 changes. 2 Fix the regulator changes for vmmc/vqmmc with disable of regulator-always-on; 3 Drop this UHS-I changes as if now. Is this ok with you. -Anand Moon > > -Doug -- 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
