On Wed, 24 Aug 2016, Maxime Ripard wrote: > Hi Lee, > > On Tue, Aug 09, 2016 at 02:48:47PM +0100, Lee Jones wrote: > > On Tue, 26 Jul 2016, Quentin Schulz wrote: > > > > > When an MFD cell has an of_compatible (meaning it is present in the Device > > > Tree), other nodes can reference it using a phandle. > > > > > > However when the MFD cell is not declared in the Device Tree, the only way > > > other nodes can reference it are by using a phandle to the MFD. Then when > > > this MFD cell tries to register itself in one framework, the registration > > > is denied by the framework because it is not matching the of_node of the > > > node which is referenced by the phandle in one of the other nodes. > > > > > > This reattaches the of_node of the MFD to the MFD cell device structure > > > when the MFD cell has no of_compatible. > > > > > > Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx> > > > --- > > > > > > We need this modification to register the thermal sensor in the thermal > > > framework. > > > > > > Added in v3. > > > > > > drivers/mfd/mfd-core.c | 14 +++++++++----- > > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > Can you show me the DT code where this is used? > > > > Is it used by a patch in this series? > > Yes and no. > > This is not used directly by any code found in those patches. > > However, those patches are actually a rewrite of an existing driver > that was there before (drivers/input/touchscreen/sun4i-ts.c), that > already had some DT bindings and was enabled in a few DT already [1]. > > The issue here is that for the new driver to be able to follow the > phandles as it used to (which is also already used [2]). Obviously, in > the usual mechanism (at least when you don't declare the mfd childs in > the DT), the childs won't have any of_node associated to it, and this > is fine in most cases. > > This is where things get messy. The MFD childs will also register to > their framework without, and then the whole phandle lookup goes nuts, > because the phandles will point to the MFD's of_node, but no one will > actually be registered anywhere with that of_node, which means that we > broke all the links expressed by the phandles. I'm concerned that this change may have unintended side-effects for existing drivers. Can you point me to the C code where this is causing an issue. Perhaps we can solve the issue without changing subsystem core code. By doing so we reduced the chance of destructive ramifications for others. > 1: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sun7i-a20.dtsi#n1520 > 2: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sun7i-a20.dtsi#n130 > -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
