On Thu, Jun 08, 2017 at 09:59:01AM +0200, Alexandre Belloni wrote: > On 08/06/2017 at 09:44:46 +0200, Daniel Lezcano wrote: > > > > +Mark Rutland, +Rob Herring > > > > > > Alexandre, Boris, have a look at https://www.spinics.net/lists/arm-kernel/msg572652.html > > > > That will tell you the story. > > > > Ok, so is the solution putting the driver back in mach-at91 were we can > do whatever we want like mach-omap2 is doing? No. And putting a driver in mach-<whatever> does not give the permission to do whatever you want. I won't tell you how OSS works, but moving code around or using another tree to circumvent a code review is just the best way to upset maintainers in general and hurt your karma. That said, I think you misunderstood my comment (or I was not clear). In the discussion given in the link above, I am in favor, somehow, to distinguish clockevent and clocksource to solve exactly what you are facing. Rob Herring told me it could be acceptable to have a property to tell if it is a clockevent or a clocksource. Mark Rutland disagreed on this. I was alone in the discussion, no consensus have been found. Now, you have a particular use case and I would like to resurrect the discussion in order to find a solution which can apply to all DT drivers. > > On Thu, Jun 08, 2017 at 07:42:36AM +0200, Boris Brezillon wrote: > > > Le Thu, 8 Jun 2017 01:17:15 +0200, > > > Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> a écrit : > > > > > > > On 07/06/2017 at 23:08:48 +0200, Daniel Lezcano wrote: > > > > > > I was going to agree but this is not flexible enough because the > > > > > > quadrature decoder always uses the first two channels. So on some > > > > > > products, we may have: > > > > > > - TCB0: > > > > > > o channels 0,1: qdec > > > > > > o channel 2: clocksource > > > > > > > > > > > > - TCB1: > > > > > > o channels 0,1: qdec > > > > > > o channel 2: clockevent > > > > > > > > > > > > This avoids wasting TCB channels. > > > > > > > > > > Ok. In this case you can check if the interrupt is specified for the node, if > > > > > yes, then it is a clockevent. > > > > > > > > > > > > > But currently it is always specified in the SoC's dtsi. I don't find > > > > that too practical to push that to the board's dts. Also, lying by > > > > omission (the IRQ is always wired) in the DT is not different from > > > > having a property selecting which timer is the clocksource and which is > > > > the clockevent. > > > > > > > > > > I agree with Alexandre here. Really, there's not much we can do to > > > detect which timer should be used as a clockevent and which one should > > > be used as a clocksource except explicitly specifying it in the DT. > > > Having an interrupt defined in one case (clockevent) and undefined in > > > the other case (clocksource), is just as hack-ish as the detection logic > > > Alexandre developed to avoid explicitly specifying the function > > > assigned to a specific timer. > > > > > > Can we please find a solution that makes everyone happy (DT, > > > clocksoure/clockevent and at91 maintainers)? > > > > > > How about adding a linux,timer-function property to specify which > > > function this timer is providing? > > > > > > Something like that for example: > > > > > > tcb0: timer@fff7c000 { > > > compatible = "atmel,at91rm9200-tcb", "simple-mfd", "syscon"; > > > #address-cells = <1>; > > > #size-cells = <0>; > > > reg = <0xfff7c000 0x100>; > > > interrupts = <18 4>; > > > clocks = <&tcb0_clk>, <&clk32k>; > > > clock-names = "t0_clk", "slow_clk"; > > > > > > timer@0 { > > > compatible = "atmel,tcb-timer"; > > > reg = <0>, <1>; > > > linux,timer-function = "clocksource"; > > > }; > > > > > > timer@2 { > > > compatible = "atmel,tcb-timer"; > > > reg = <2>; > > > linux,timer-function = "clockevent"; > > > }; > > > }; > > > > > > Alternatively, we could have a property or a node in chosen describing which > > > timer should be used: > > > > > > chosen { > > > clockevent { > > > timer = <&timer2>; > > > }; > > > > > > clocksource { > > > timer = <&timer0>; > > > }; > > > > > > /* > > > * or > > > * > > > * clockevent = <&timer2>; > > > * clocksource = <&timer0>; > > > * > > > * but I think the clocksource/clockevent node approach > > > * is more future proof in case we need to add extra > > > * information like the expected resolution/precision or > > > * anything that could be tweakable. > > > */ > > > }; > > > > > > tcb0: timer@fff7c000 { > > > compatible = "atmel,at91rm9200-tcb", "simple-mfd", "syscon"; > > > #address-cells = <1>; > > > #size-cells = <0>; > > > reg = <0xfff7c000 0x100>; > > > interrupts = <18 4>; > > > clocks = <&tcb0_clk>, <&clk32k>; > > > clock-names = "t0_clk", "slow_clk"; > > > > > > timer0: timer@0 { > > > compatible = "atmel,tcb-timer"; > > > reg = <0>, <1>; > > > }; > > > > > > timer2: timer@2 { > > > compatible = "atmel,tcb-timer"; > > > reg = <2>; > > > }; > > > }; > > > > -- > > > > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > > <http://twitter.com/#!/linaroorg> Twitter | > > <http://www.linaro.org/linaro-blog/> Blog > > -- > Alexandre Belloni, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
