On Fri, Oct 25, 2013 at 08:39:51AM +0200, Lothar Waßmann wrote: > Hi, > > Thierry Reding wrote: > > On Thu, Oct 24, 2013 at 02:42:13PM +0200, Denis Carikli wrote: > > > Cc: Rob Herring <[email protected]> > > > Cc: Pawel Moll <[email protected]> > > > Cc: Mark Rutland <[email protected]> > > > Cc: Stephen Warren <[email protected]> > > > Cc: Ian Campbell <[email protected]> > > > Cc: [email protected] > > > Cc: Dmitry Torokhov <[email protected]> > > > Cc: [email protected] > > > Cc: Sascha Hauer <[email protected]> > > > Cc: [email protected] > > > Cc: Lothar Waßmann <[email protected]> > > > Cc: Eric Bénard <[email protected]> > > > Signed-off-by: Denis Carikli <[email protected]> > > > --- > > > ChangeLog v6->v7: > > > - One small whitespace cleanup. > > > - The properties specific to that driver are now prefixed with "ti,". > > > - The ti,fuzzy property has now better documentation. > > > --- > > > .../bindings/input/touchscreen/tsc2007.txt | 45 +++++ > > > drivers/input/touchscreen/tsc2007.c | 194 > > > +++++++++++++++----- > > > 2 files changed, 198 insertions(+), 41 deletions(-) > > > create mode 100644 > > > Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt > > > > > > diff --git > > > a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt > > > b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt > > > new file mode 100644 > > > index 0000000..516b63b > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt > > > @@ -0,0 +1,45 @@ > > > +* Texas Instruments tsc2007 touchscreen controller > > > + > > > +Required properties: > > > +- compatible: must be "ti,tsc2007". > > > +- reg: I2C address of the chip. > > > +- ti,x-plate-ohms: X-plate resistance in ohms. > > > + > > > +Optional properties: > > > +- gpios: the interrupt gpio the chip is connected to (trough the penirq > > > pin) > > > + (see GPIO binding[2] for more details). > > > +- interrupt-parent: the phandle for the gpio controller > > > + (see interrupt binding[1]). > > > +- interrupts: (gpio) interrupt to which the chip is connected > > > + (see interrupt binding[1]). > > > +- pinctrl-0: Should specify pin control groups used for the gpio > > > + (see pinctrl bindings[0]). > > > +- pinctrl-names: Should contain only one value - "default" > > > + (see pinctrl bindings[0]). > > > > Also I haven't seen a response as to why this can't be handled by the > > GPIO driver. Adding Linus Walleij, perhaps he knows a more definitive > > answer. > > > > Linus, the issue here is that the pinctrl properties for this chip are > > supposed to pinmux the pendown GPIO for this chip. I was under the > > impression that this should be handled by the GPIO controller itself, so > > that when gpio_request() was called on a pin it would be the GPIO > > controller driver's responsibility to pinmux it appropriately. > > > When a GPIO is requested the GPIO layer cannot know what it is > requested for and how the pinmux for the pin function should be > configured (pullups, drive strength, ...). A pin may have multiple > functions depending on what modules are plugged into a baseboard.
But GPIO is one specific function of a given pin, isn't it? > Thus the pinctrl binding needs to be with the driver that uses the pin. I wonder if this really needs to be dynamically configured depending on the driver. Properties like pullups and driver strength can potentially harm hardware when they're wrong, so relying on the driver's probe to configure them correctly doesn't sound very safe. It's always possible to disable the device (either via modifying the DTS or by having the bootloader patch it). That means the driver won't be probed at all, and therefore none of the pinctrl or pinmux settings will be applied. Thierry
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