[RFC PATCH 0/3] devicetree, qcomm PMIC: fix node name conflict
From: Frank Rowand
Date: Tue May 06 2014 - 20:48:50 EST
An issue with the path of SPMI nodes under /sys/bus/... was reported in
https://lkml.org/lkml/2014/4/23/312. The symptom is that two different
grandchild nodes of the spmi with the same node-name@unit-address will
result in attempting to create duplicate links at
/sys/bus/platform/devices/unit-address.node-name. It turns out that the
specific example provided might not be an expected configuration for
current hardware, but the reported trap remains an issue.
I have been poking at the problem, trying to figure out how to cleanly
fix the issue without breaking devicetree device creation.
The first patch in the series is the one that may be a very bad idea. Or
it may help show the way forward to deal with what I think is the major
underlying problem. I have not finished investigating the possible negative
side effects. And I am still thinking whether this is a conceptually good
approach, or whether it is simply an expediant hack that hides the underlying
problem. But I am throwing this out prematurely because I have mentioned
it to several people, and I want to make it visible to everyone involved.
The underlying architectural problem (in my opinion) is that a lot of devices
are created by the device tree infrastructure as platform devices, when they
truly should not be platform devices. They should not be platform devices
because they are not physically on a platform bus, they are instead somewhere
below some other bus. The first patch in this series is a hack which
results in the devices still being represented by "struct platform_device"
objects, but with a link to their parent's "struct bus_type" instead of
to &platform_bus_type.
The second patch does not require the first patch. The second patch provides
a mechanism to allow subsystems to provide a method of naming devices to
avoid name collisions.
The third patch provides an example of a subsystem using the new feature
provided by the second patch.
The resulting device naming and soft links from applying all three patches,
or just the second and third patches are:
===== no patches applied:
$ ls /sys/devices/
ARMv7 Krait cpu-pmu.1 platform software tracepoint
breakpoint cpus.0 soc.2 system virtual
$ ls /sys/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
100.qcom,revid driver subsystem
3100.qcom,pm8x41-adc-usr gpios.18 uevent
6000.qcom,rtc power
$ ls /sys/bus/platform/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
100.qcom,revid driver subsystem
3100.qcom,pm8x41-adc-usr gpios.18 uevent
6000.qcom,rtc power
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-01/
b040.pm8xxx-pwm driver uevent
d000.pm8xxx-pwm-led power
d800.pm8xxx-wled subsystem
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-04/
driver power subsystem uevent
$ ls /sys/bus/spmi/devices/
0-00 0-01 0-04 spmi-0
$ ls /sys/bus/platform/devices/
100.qcom,revid fc4cf000.qcom,spmi
3100.qcom,pm8x41-adc-usr fd484000.hwlock
6000.qcom,rtc fd510000.pinctrl
alarmtimer fd8c0000.clock-controller
b040.pm8xxx-pwm gpio_keys.5
cpu-pmu.1 gpios.18
cpus.0 iio-thermal.4
d000.pm8xxx-pwm-led pm8841-s1.6
d800.pm8xxx-wled pm8841-s2.7
f9000000.interrupt-controller pm8941-l3.11
f9011000.smem pm8941-l6.12
f9012000.regulator reg-dummy
f9020000.timer regulator-l11.14
f9088000.clock-controller regulator-l19.15
f9098000.clock-controller regulator-l20.16
f90a8000.clock-controller regulator-l22.17
f90b8000.clock-controller regulator-l9.13
f9824900.sdhc regulator-s1.8
f991e000.serial regulator-s2.9
f9924000.i2c2 regulator-s3.10
f9928000.i2c6 regulatory.0
f9bff000.rng snd-soc-dummy
fc400000.clock-controller soc.2
fc4281d0.qcom,mpm timer.3
fc4ab000.restart
===== all three patches applied:
$ ls /sys/devices/
ARMv7 Krait cpu-pmu.1 platform software tracepoint
breakpoint cpus.0 soc.2 system virtual
$ ls /sys/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
0-00:100.qcom,revid driver
0-00:3100.qcom,pm8x41-adc-usr power
0-00:6000.qcom,rtc subsystem
0-00:gpios uevent
$ ls /sys/bus/platform/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
0-00:100.qcom,revid driver
0-00:3100.qcom,pm8x41-adc-usr power
0-00:6000.qcom,rtc subsystem
0-00:gpios uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-01/
0-01:b040.pm8xxx-pwm driver uevent
0-01:d000.pm8xxx-pwm-led power
0-01:d800.pm8xxx-wled subsystem
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-04/
0-04:100.qcom,revid power uevent
driver subsystem
$ ls /sys/bus/spmi/devices/
0-00 0-01:b040.pm8xxx-pwm
0-00:100.qcom,revid 0-01:d000.pm8xxx-pwm-led
0-00:3100.qcom,pm8x41-adc-usr 0-01:d800.pm8xxx-wled
0-00:6000.qcom,rtc 0-04
0-00:gpios 0-04:100.qcom,revid
0-01 spmi-0
$ ls /sys/bus/platform/devices/
alarmtimer f9bff000.rng
cpu-pmu.1 fc400000.clock-controller
cpus.0 fc4281d0.qcom,mpm
f9000000.interrupt-controller fc4ab000.restart
f9011000.smem fc4cf000.qcom,spmi
f9012000.regulator fd484000.hwlock
f9020000.timer fd510000.pinctrl
f9088000.clock-controller fd8c0000.clock-controller
f9098000.clock-controller gpio_keys.5
f90a8000.clock-controller iio-thermal.4
f90b8000.clock-controller reg-dummy
f9824900.sdhc regulatory.0
f991e000.serial snd-soc-dummy
f9924000.i2c2 soc.2
f9928000.i2c6 timer.3
===== patches 2 and 3 applied:
$ ls /sys/devices/
ARMv7 Krait cpu-pmu.1 platform software tracepoint
breakpoint cpus.0 soc.2 system virtual
$ ls /sys/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
0-00:100.qcom,revid driver
0-00:3100.qcom,pm8x41-adc-usr power
0-00:6000.qcom,rtc subsystem
0-00:gpios uevent
$ ls /sys/bus/platform/devices/soc.2/
f9000000.interrupt-controller fc4281d0.qcom,mpm
f9011000.smem fc4ab000.restart
f9012000.regulator fc4cf000.qcom,spmi
f9020000.timer fd484000.hwlock
f9088000.clock-controller fd510000.pinctrl
f9098000.clock-controller fd8c0000.clock-controller
f90a8000.clock-controller gpio_keys.5
f90b8000.clock-controller iio-thermal.4
f9824900.sdhc modalias
f991e000.serial power
f9924000.i2c2 subsystem
f9928000.i2c6 timer.3
f9bff000.rng uevent
fc400000.clock-controller
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/
driver modalias power spmi-0 subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/
0-00 0-01 0-04 power subsystem uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-00/
0-00:100.qcom,revid driver
0-00:3100.qcom,pm8x41-adc-usr power
0-00:6000.qcom,rtc subsystem
0-00:gpios uevent
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-01/
0-01:b040.pm8xxx-pwm driver uevent
0-01:d000.pm8xxx-pwm-led power
0-01:d800.pm8xxx-wled subsystem
$ ls /sys/bus/platform/devices/soc.2/fc4cf000.qcom,spmi/spmi-0/0-04/
0-04:100.qcom,revid power uevent
driver subsystem
$ ls /sys/bus/spmi/devices/
0-00 0-01 0-04 spmi-0
$ ls /sys/bus/platform/devices/
0-00:100.qcom,revid fc4281d0.qcom,mpm
0-00:3100.qcom,pm8x41-adc-usr fc4ab000.restart
0-00:6000.qcom,rtc fc4cf000.qcom,spmi
0-00:gpios fd484000.hwlock
0-01:b040.pm8xxx-pwm fd510000.pinctrl
0-01:d000.pm8xxx-pwm-led fd8c0000.clock-controller
0-01:d800.pm8xxx-wled gpio_keys.5
0-04:100.qcom,revid iio-thermal.4
alarmtimer pm8841-s1.6
cpu-pmu.1 pm8841-s2.7
cpus.0 pm8941-l3.11
f9000000.interrupt-controller pm8941-l6.12
f9011000.smem reg-dummy
f9012000.regulator regulator-l11.14
f9020000.timer regulator-l19.15
f9088000.clock-controller regulator-l20.16
f9098000.clock-controller regulator-l22.17
f90a8000.clock-controller regulator-l9.13
f90b8000.clock-controller regulator-s1.8
f9824900.sdhc regulator-s2.9
f991e000.serial regulator-s3.10
f9924000.i2c2 regulatory.0
f9928000.i2c6 snd-soc-dummy
f9bff000.rng soc.2
fc400000.clock-controller timer.3
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