Hi Thierry, > Subject: Re: [PATCH 4/4] Documentation: Add device tree bindings for > Freescale FTM PWM > > On Thu, Aug 22, 2013 at 08:26:10AM +0200, Sascha Hauer wrote: > > On Thu, Aug 22, 2013 at 02:55:42AM +0000, Xiubo Li-B47053 wrote: > > > Hi Tomasz, > > > > > > Thanks for your comments. > > > > > > > > > > Could you explain meaning of this property more precisely? I'm > > > > interested especially how is this related to the PWM IP block and > boards. > > > > > > > > > > Yes. > > > There are 8 channels most. While the pinctrls of 4th and 5th > > > channels could be used by uart's Rx and Tx, then these 2 channels > > > won't be used for pwm output, so there will be 6 channels available > by the pwm. > > > Thus, the pwm chip will register only 6 pwms(6 channels) > > > most("fsl,pwm-channel-orders = {0 1 2 3 6 7}").And also the "fsl,pwm- > channel-number" will be 6. > > > > If the chip has eight PWMs I would register all of them. If some of > > them are not routed out by the pinmux then just nothing happens if you > > use them. In a sane devicetree they won't be referenced anyway when > > they are not routed out of the SoC. > > In that case, shouldn't this be hooked up to the pinctrl subsystem as > well? As I understand the above, the logical thing would be for each PWM > channel's .request() operation to configure the pinmuxing appropriately. > And if it can't be configured as necessary then .request() should return > an error (or propagate the error from the pinctrl subsystem). > That's maybe better, if so, the pinctrl configuration must be split into two steps: 1, get the channel pinctrl "active" and "idle" states by callig pinctrl_lookup_state() in .request(). 2, select the proper state in .enable()/.disable(). Thanks very much. -- Best Regards. Xiubo -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html