On Tue, Aug 27, 2013 at 11:50:40AM +0100, Laurent Pinchart wrote: > Hi Mark, > > On Tuesday 27 August 2013 11:39:49 Mark Rutland wrote: > > On Sat, Aug 24, 2013 at 03:13:11PM +0100, Tomasz Figa wrote: > > > On Saturday 24 of August 2013 02:54:07 Laurent Pinchart wrote: > > > > On Saturday 24 August 2013 02:41:59 Tomasz Figa wrote: > > > > > On Tuesday 20 of August 2013 01:04:54 Laurent Pinchart wrote: > > > > > > Add DT bindings for the pcf857x-compatible chips and parse the > > > > > > device tree node in the driver. > > > > > > > > > > > > Signed-off-by: Laurent Pinchart > > > > > > <laurent.pinchart+rene...@ideasonboard.com> > > > > > > --- > > > > > > > > > > > > .../devicetree/bindings/gpio/gpio-pcf857x.txt | 71 +++++++++++ > > > > > > drivers/gpio/gpio-pcf857x.c | 57 +++++++++-- > > > > > > 2 files changed, 119 insertions(+), 9 deletions(-) > > > > > > create mode 100644 > > > > > > Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > > > > b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt new file > > > > > > mode 100644 > > > > > > index 0000000..df94462 > > > > > > --- /dev/null > > > > > > +++ b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt > > > > > > @@ -0,0 +1,71 @@ > > > > > > > > [snip] > > > > > > > > > > + - pins-initial-state: Bitmask that specifies the initial state of > > > > > > + each pin. When a bit is set to zero, the corresponding pin will > > > > > > be > > > > > > + initialized to the input (pulled-up) state. When the bit is > > > > > > set to + one, the pin will be initialized the the low-level > > > > > > output state. If + the property is not specified all pins will > > > > > > be initialized to the + input state. > > > > > > > > > > Hmm, do you actually need to know whether those pins are outputs or > > > > > inputs before they get used for first time? I believe any driver > > > > > using GPIO will call gpio_direction_{in,out}put() before it starts > > > > > using the pin, which will initialize the pin to a known state. > > > > > > > > > > What I'd suggest is making the driver handle this by having a bit mask > > > > > that marks states of pins as defined and flagging all pins as > > > > > undefined by default. Then any call to gpio_direction_output() or > > > > > _input() would mark it as defined and direction of the pin could be > > > > > stored in internal driver structures. > > > > > > > > The problem is that all pins are controlled through a single I2C write. > > > > Setting the direction of a pin will set the direction of all other pins. > > > > I thus need to know what the initial settings are to avoid glitches. > > > > I guess it's not possible to read the initial state from the hardware? > > I wish. Unfortunately it can only be written.
What a shame :( Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/