On Fri, Apr 1, 2011 at 11:56 AM, Grant Likely <grant.likely@xxxxxxxxxxxx> wrote: > On Fri, Apr 1, 2011 at 11:47 AM, Andres Salomon <dilinger@xxxxxxxxxx> wrote: >> On Fri, 1 Apr 2011 13:20:31 +0200 >> Samuel Ortiz <sameo@xxxxxxxxxxxxxxx> wrote: >> >>> Hi Grant, >>> >>> On Thu, Mar 31, 2011 at 05:05:22PM -0600, Grant Likely wrote: >> [...] >>> > Gah. Not all devices instantiated via mfd will be an mfd device, >>> > which means that the driver may very well expect an *entirely >>> > different* platform_device pointer; which further means a very high >>> > potential of incorrectly dereferenced structures (as evidenced by a >>> > patch series that is not bisectable). For instance, the xilinx ip >>> > cores are used by more than just mfd. >>> I agree. Since the vast majority of the MFD subdevices are MFD >>> specific IPs, I overlooked that part. The impacted drivers are the >>> timberdale and the DaVinci voice codec ones. > > Another option is you could do this for MFD devices: > > struct mfd_device { > struct platform_devce pdev; > struct mfd_cell *cell; > }; > > However, that requires that drivers using the mfd_cell will *never* > get instantiated outside of the mfd infrastructure, and there is no > way to protect against this so it is probably a bad idea. > > Or, mfd_cell could be added to platform_device directly which would > *by far* be the safest option at the cost of every platform_device > having a mostly unused mfd_cell pointer. Not a significant cost in my > opinion. > > One last option is I'm prototyping a way to add type-safe structure > pointers to a device, but that requires nasty CPP tricks and it's not > complete yet. The cure might be worse than the disease here. And yet another option is to create a mfd_bus_type, but that probably isn't helpful since the one of the purposes of MFDs is that it is a collection of non-detectable memory mapped devices that platform_bus_type is intended to handle. g. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html