Messages in this thread |  | | Subject | Re: Strange location and name for platform devices when device-tree is used. | From | Benjamin Herrenschmidt <> | Date | Fri, 01 Nov 2013 16:08:36 +1100 |
| |
On Fri, 2013-11-01 at 16:03 +1100, NeilBrown wrote:
> Do you mean we could allow multiple devices on the one bus to have the same > name, but get sysfs to notice and de-duplicate by mangling one name? I don't > think I like that but I might have misunderstood.
What other option do we have ?
> On my device I seem to have some platform devices registered through > device-tree, and some registered through platform_device_add (e.g. > 'alarmtimer'). Guaranteeing they remain disjoint sets if the kernel is > allowed to evolve independently of the devicetree might be tricky.... > Maybe we need "/sys/devices/platform" and "/sys/devices/dt_platform" ??
No, I think device-tree created platform devices should go to /sys/devices/platform like the "classic" ones.
The problem is really how to deal with potential name duplication. We could try to register, if we get -EEXIST (assuming sysfs returns the right stuff), try again with ".1" etc...
> Hoping someone who understands the device model better than me will help.
Greg ? :-)
.../...
> The 'backlight' device is a virtual device. It uses a 'pwm' device to > provide the variable brightness to the back light. > > The 'pwm' device itself is virtual, making use of a 'dmtimer' to provide the > timing... The timer device (timer11 in omap3.dtsi) has a 'reg' property. > > A random example from current mainline is > arch/arm/boot/dts/am335x-evmsk.dts > which has 'backlight' as a virtual device compatible with pwm-backlight. > It also has 'gpio-keys', 'gpio-leds', and 'regulator-fixed' compatible > virtual devices. They seem fairly common.
Ok.
Cheers, Ben.
> Thanks, > NeilBrown > > > > > > Cheers, > > Ben. > > > > > Cheers, > > > Ben. > > > > > > > Any help understanding and/or fixing this discrepancy greatly appreciated. > > > > > > > > The change of name is particularly annoying to me because one of my platform > > > > devices is a pwm_bl.c backlight. With a boardfile I > > > > get /sys/class/pwm_backlight. With devicetree the best I can get > > > > is /sys/class/pwm_backlight.23 (or similar). It would be really nice to have > > > > a more stable and sensible name here. > > > > > >
|  |