Messages in this thread | | | Date | Tue, 16 Aug 2022 11:04:18 +0200 | From | Michael Walle <> | Subject | Re: [PATCH v3 3/8] arm64: dts: ls1028a: add flextimer based pwm nodes |
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Am 2022-07-28 11:33, schrieb Michael Walle: > Hi, > > sorry for digging up this old thread. But I've noticed some > inconsistencies here while syncing the device tree with u-boot. > >>> On Wed, Apr 13, 2022 at 06:07:20PM +0000, Leo Li wrote: >>> > > arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi:1210.21-1219.5: >>> > > Warning >>> > > (unique_unit_address): /soc/pwm@2800000: duplicate unit-address >>> > > (also used in node /soc/timer@2800000) >>> > > arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi:1221.21-1230.5: >>> > > Warning >>> > > (unique_unit_address): /soc/pwm@2810000: duplicate unit-address >>> > > (also used in node /soc/timer@2810000) >>> > >>> > Well, this is similar situation as pcie. The flextimer controller can >>> > be used as timer, PWM or alarm. We have separate drivers and bindings >>> > for these modes which resulted in different nodes for the same >>> > controller. >>> >>> I think the mfd framework can address the situation where multiple >>> drivers, >>> with multiple functionalities, want access to the same memory region? >> >> I know mfd is used for device providing multiple functions at the same >> time. I'm not sure if it can help dealing with the one function at a >> time >> scenario. > > Funnily enough, I had the same concern: > https://lore.kernel.org/lkml/92eaa24876a823aa5833435f51095812@walle.cc/ > > Anyway, I have a few questions about the device tree here: > >> + rtc_clk: rtc-clk { >> + compatible = "fixed-clock"; >> + #clock-cells = <0>; >> + clock-frequency = <32768>; >> + clock-output-names = "rtc_clk"; >> + }; >> + > > Is that an internal clock? I've checked the RDB schematics and the > RTC clock output is not connected to anything. The RM of the LS1028A > mentions the fixed clock input of the flex timer, but it doesn't say > where it is connected to. It just says there is no > "internally-generated > secure clock" support on any of the timer modules. > > In ch19.3 it also says "For the chip-specific implementation details of > this module's instances, see the chip configuration information". But > I'm not sure where to find this. > > >> + pwm0: pwm@2800000 { >> + compatible = "fsl,vf610-ftm-pwm"; >> + #pwm-cells = <3>; >> + reg = <0x0 0x2800000 0x0 0x10000>; >> + clock-names = "ftm_sys", "ftm_ext", >> + "ftm_fix", "ftm_cnt_clk_en"; >> + clocks = <&clockgen 4 1>, <&clockgen 4 1>, >> + <&rtc_clk>, <&clockgen 4 1>; > > ftm_ext seems to be the (optional) external clock, eg FTMn_EXTCLK. Why > is > it connected to <&clockgen 4 1>? That doesn't make sense. The driver > itself, won't probe if the clock isn't there either and assumes that > the > external clock is always there. That seems wrong, too. > > Can you shed some light on this?
Ping.
-michael
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