Re: [PATCH]dts: add bcm2835-pwm bindings

From: Stephen Warren
Date: Tue Jan 13 2015 - 11:18:43 EST


On 01/13/2015 08:40 AM, Bart Tanghe wrote:
On 01/10/2015 05:38 PM, Stephen Warren wrote:
On 01/05/2015 08:33 AM, Bart Tanghe wrote:
To probe the bcm2835-pwm driver properly, this dts bindings has to be added
to the bcm2835 dtsi file.
In expectation of a bcm2835 clock driver, I've added fixed-clock clock binding.
To change the status of the gpio pins into pwm output pins, some additional
bindings has to be added but this has not to be done automatically.
Is it possible to document this bindings somewhere?

The pinctrl bindings allow you to do this. They're documented in:

Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt

pinctrl setup would typically be added to the board file (i.e.
arch/arm/boot/dts/bcm2835-rpi-b.dts) rather than the SoC file. I think
on the RPi, the pins that can generate PWM aren't dedicated to PWM by
the RPi board design (they could be GPIOs and probably other functions
too) so we probably need to leave it up to individual users to add PWM
configuration to their DT, if/when they use the PWM feature.


Indeed, the pins aren't dedicated to pwm and can be used for other functions.
Is it usefull to add the pwm pinctrl description to
Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt or is this
useless?

As far as I can tell, that file already describes everything required to configure those pins as PWM (or indeed any pins as any function). Can you expand on what you think is missing?
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