Hi, Arnd Bergmann <arnd@xxxxxxxx> writes: > On Thursday 28 April 2016 15:16:12 Russell King - ARM Linux wrote: >> On Thu, Apr 28, 2016 at 09:37:08AM +0300, Felipe Balbi wrote: >> > >> > Hi, >> > >> > Arnd Bergmann <arnd@xxxxxxxx> writes: >> > > pointer and pass that in platform_data. This is really easy, it's >> > >> > Sorry but passing a struct device pointer in platform_data is >> > ridiculous. Not to mention that, as I said before, we can't assume which >> > device to pass to xhci_plat in the first place. It might be dwc->dev and >> > it might be dwc->dev->parent. >> >> +1. Passing an unref-counted struct device through platform data is >> totally mad, Arnd you're off your rocker if you think that's a good >> idea. What's more is that there's no way to properly refcount the >> thing. > > It's the parent device (or NULL), there is no way it can ever go away as > it's already refcounted through the device subsystem by the creation > of the child device. you're assuming that based on what we have today. We could get into a situation where we need to use a completely unrelated device and the problem exists again. > I do realize that it's a hack, but the idea is to get rid of that > as soon as possibly by fixing the way the xhci device is probe so > we no longer need to fake a platform_device as the child here and > can just use the device itself. okay, let me try to be extra clear here: We will *not* remove the extra platform_device because it actually *does* exist and helps me hide/abstract a bunch of details and make assumptions about order of certain events. We have already gone through that in the past when I explained why I wrote dwc3 the way it is; if you need a refresher, there are mailing list archives for that. Moreover, this same problem exists for anything under drivers/mfd. It just so happens that they're usually some i2c or spi device which don't do DMA by themselves. -- balbi
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