Because of this change, the driver now expects a pinctrl device reference in the mmc controller's device tree node; without it, it will bail out. This could break existing setups that don't specify it because it "just worked" up until now. So currently I just let the old behavior fall away because this is a staging driver. But if this is a problem, the old behavior could be added back as a fallback. This is version 2 of a patchset that I requested feedback for about a month ago. Please review as if they are a new patchset; all the patches were rebased several times and a couple new correctness fixes added. The TODO list is largely unchanged, aside from the couple of TODO comments in the code that I have addressed. Ultimately, I think this driver could potentially be merged with the "real" mtk-mmc driver as the TODO suggests, but someone who is more familiar with the IP core will have to do that. Mediatek documentation (that I can find) is very sparse. This is ready to merge if there is no other feedback!
