Searched hist:"76 abbdde2d95a3807d0dc6bf9f84d03d0dbd4f3d" (Results 1 – 2 of 2) sorted by relevance
| /linux/Documentation/ABI/testing/ |
| H A D | sysfs-class-pwm | 76abbdde2d95a3807d0dc6bf9f84d03d0dbd4f3d Tue Jun 11 19:38:59 CEST 2013 H Hartley Sweeten <hartleys@visionengravers.com> pwm: Add sysfs interface
Add a simple sysfs interface to the generic PWM framework.
/sys/class/pwm/
`-- pwmchipN/ for each PWM chip
|-- export (w/o) ask the kernel to export a PWM channel
|-- npwm (r/o) number of PWM channels in this PWM chip
|-- pwmX/ for each exported PWM channel
| |-- duty_cycle (r/w) duty cycle (in nanoseconds)
| |-- enable (r/w) enable/disable PWM
| |-- period (r/w) period (in nanoseconds)
| `-- polarity (r/w) polarity of PWM (normal/inversed)
`-- unexport (w/o) return a PWM channel to the kernel
Based on work by Lars Poeschel.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Lars Poeschel <poeschel@lemonage.de>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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| /linux/drivers/pwm/ |
| H A D | pwm-pxa.c | diff 1e185c7aafbb56580feaa5bdbc9e4b1d8efaf710 Thu Aug 08 19:00:37 CEST 2013 Mike Dunn <mikedunn@newsguy.com> pwm: pxa: Use module_platform_driver
Commit 76abbdde2d95a3807d0dc6bf9f84d03d0dbd4f3d
pwm: Add sysfs interface
causes a kernel oops due to a null pointer dereference on PXA platforms.
This happens because the class added by the patch is registered in a
subsys_initcall (initcall4), but the pxa pwm driver is registered in
arch_initcall (initcall3). If the class is not registered before the
driver probe function runs, the oops occurs in device_add() when the
uninitialized pointers in struct class are dereferenced. I don't see a
reason that the driver must be an arch_initcall, so this patch makes it
a regular module_platform_driver (initcall6), preventing the oops.
Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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