Hello Doug, On 08/19/2014 06:26 PM, Doug Anderson wrote: > > While your change is correct, I have a worry that it will break things > if it's merged before some patches that Yuvaraj is working on. > > Specifically the problem on pit and pi (and any exynos5250 / 5420 / > 5800 / ... boards using the built-in "card detect") is that the card > detect line is on the same power rail as "vqmmc". That means you > can't turn off vqmmc if you still need to be able to detect card > insertions. > > ...but you can't turn off vmmc without turning off vqmmc, otherwise > current will leak through the IO lines into the card, which is bad. > > > Right now the SDMMC core will try to turn off power to the card at two times: > 1. when the card is ejected > 2. when it's trying to reset the card > > > Obviously the first problem is a huge problem on exynos because it > means that we won't be able to detect card insertions. ...but we > still want to turn the power off from #2. To really fix the problem I > think the core needs to be extended to treat the above as two separate > cases. > Thanks a lot for the explanation, now I remember reading about this on thread "[PATCH 2/3] mmc: dw_mmc: Dont cut off vqmmc and vmmc" [0] but didn't think in the side effect when adding this patch... > > Your patch might work at the moment because I think dw_mmc doesn't > actually try to turn off these rails with the main SDMMC core asks it > to. ...but I still worry about merging them before Yuvaraj's changes > are ready. > Agreed, I'll drop this patch and wait for Yuvaraj's series to land first. Yuvaraj's "UHS support for dw_mmc driver" series that should contain the change you are referring had the issue that when the tps65090 fet4 was used as vmmc-supply, mmc_regulator_get_supply() was failing. I posted a bunch of patches to fix that issue and there were already merged on the relevant trees and shows on linux-next: e1da8cd mmc: core: Use regulator_get_voltage() if OCR mask is empty. a130548 ARM: dts: Improve Peach Pit and Pi power scheme 4f2352c regulator: tps65090: Set voltage for fixed regulators 26988ef regulator: core: Allow to get voltage count and list from parent e303996 regulator: core: Get voltage from parent if not available So hopefully his series have no blockers anymore. > > -Doug > Best regards, Javier [0]: https://www.mail-archive.com/linux-mmc@xxxxxxxxxxxxxxx/msg27152.html -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |