| Message ID | 20170620011837.14010-2-chris.packham@alliedtelesis.co.nz |
|---|---|
| State | Superseded |
| Headers | show |
> + - reset-gpios : gpio specifier for gpio connected to RESET_N pin.
What about the 'active' state that Rob mentioned in his last review?
On 22/06/17 20:23, Wolfram Sang wrote: > >> + - reset-gpios : gpio specifier for gpio connected to RESET_N pin. > > What about the 'active' state that Rob mentioned in his last review? > My intention was that by saying it is connected to the RESET_N bin the active state is covered. I personally always get a little confused when talking about reset lines. The _N denotes that the line is active low but because it is a reset line writing 1 releases the reset so from a what-the-user-wants perspective it's active high. dt-binding-wise what we want here is GPIO_ACTIVE_HIGH, as in the driver writes 1 to release reset so don't do any polarity inversion. I'd be happy do add something to that effect in a v3 but I actually felt saying the gpio is connected to RESET_N was less ambiguous.
On Thu, Jun 22, 2017 at 09:20:59PM +0000, Chris Packham wrote: > On 22/06/17 20:23, Wolfram Sang wrote: > > > >> + - reset-gpios : gpio specifier for gpio connected to RESET_N pin. > > > > What about the 'active' state that Rob mentioned in his last review? > > > > My intention was that by saying it is connected to the RESET_N bin the > active state is covered. > > I personally always get a little confused when talking about reset > lines. The _N denotes that the line is active low but because it is a > reset line writing 1 releases the reset so from a what-the-user-wants > perspective it's active high. > > dt-binding-wise what we want here is GPIO_ACTIVE_HIGH, as in the driver > writes 1 to release reset so don't do any polarity inversion. I'd be > happy do add something to that effect in a v3 but I actually felt saying > the gpio is connected to RESET_N was less ambiguous. Okay. Thanks for the explanation. I am fine with it but I'll leave the final decision to Rob.
On Thu, Jun 22, 2017 at 09:20:59PM +0000, Chris Packham wrote: > On 22/06/17 20:23, Wolfram Sang wrote: > > > >> + - reset-gpios : gpio specifier for gpio connected to RESET_N pin. > > > > What about the 'active' state that Rob mentioned in his last review? > > > > My intention was that by saying it is connected to the RESET_N bin the > active state is covered. I would say okay, but based on below it's not. > I personally always get a little confused when talking about reset > lines. The _N denotes that the line is active low but because it is a > reset line writing 1 releases the reset so from a what-the-user-wants > perspective it's active high. > > dt-binding-wise what we want here is GPIO_ACTIVE_HIGH, as in the driver > writes 1 to release reset so don't do any polarity inversion. I'd be > happy do add something to that effect in a v3 but I actually felt saying > the gpio is connected to RESET_N was less ambiguous. No, the driver is wrong. The binding should say GPIO_ACTIVE_LOW because that is how the pin is defined. The driver needs to set it to inactive. Rob
diff --git a/Documentation/devicetree/bindings/i2c/i2c-pca-platform.txt b/Documentation/devicetree/bindings/i2c/i2c-pca-platform.txt new file mode 100644 index 000000000000..86abf249b194 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-pca-platform.txt @@ -0,0 +1,18 @@ +* NXP PCA PCA9564/PCA9665 I2C controller + +The PCA9564/PCA9665 serves as an interface between most standard +parallel-bus microcontrollers/microprocessors and the serial I2C-bus +and allows the parallel bus system to communicate bi-directionally +with the I2C-bus. + +Required properties : + + - reg : Offset and length of the register set for the device + - compatible : one of "nxp,pca9564" or "nxp,pca9665" + +Optional properties + - interrupts : the interrupt number + - interrupt-parent : the phandle for the interrupt controller. + If an interrupt is not specified polling will be used. + - reset-gpios : gpio specifier for gpio connected to RESET_N pin. + - clock-frequency : I2C bus frequency.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> --- Changes in v2: - Split dt-binding to separate patch, use "reset-gpios" instead of "gpios". .../devicetree/bindings/i2c/i2c-pca-platform.txt | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-pca-platform.txt