On Thu, 24 May 2012, Ohad Ben-Cohen wrote: > Hi Guennadi, > > On Thu, May 24, 2012 at 6:42 PM, Guennadi Liakhovetski > <g.liakhovetski@xxxxxx> wrote: > > Yes, exactly, in certain cases. And when it's not hard-wired? > > We don't support this yet. Ic, so, basically, for boards with normal SD-card slots SDIO-card runtime PM is not supported. > Daniel suggested using either black or white listing (based on > vendor/device id presumably) so we can support regular cards without > breaking others, but I'm not sure if Daniel had any free cycles to > look into it. > > > Because with pluggable cards one flag is not enough. I think, you need (1) > > board capability to switch power, and (2) driver's allowance to power the > > card down. > ... > > The problem of hot-pluggable cards. One card / driver combination will > > support powering down at runtime, another one will not. > > Ah ok now I understand you, thanks for the explanation. Sorry, I had to clarify the situation first with the flags before I could formulate the problem properly. > Whether or not to involve the driver here probably depends on the > actual hardware requirements. E.g., if the vendor/device id is enough > information, then we might be able to implement this below the drivers > without involving them. But in case only the driver could tell between > variants of specific chips, then a generic white/black listing might > not be enough. I think it'd be better to go with driver-assisted PM straight away instead of implementing black-/white-lists to later find out about cards with the same IDs and different behaviour. > Feel free to propose a solution, but please back it up with real > hardware and show that it satisfies the MMC_CAP_POWER_OFF_CARD issues > we had in the past. Thanks:-) It was important for me in the first place to understand the problem. Now that the problem has become clearer we can think about whether, when and how to solve it and who shall do it:-) Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- 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
