On Wed, Jun 15, 2016 at 7:37 AM, Thierry Reding <[email protected]> wrote: > On Tue, Jun 14, 2016 at 07:12:04PM -0700, Greg KH wrote: >> From: David Hsu <[email protected]> >> >> Pwm channels don't send uevents when exported, this change adds the >> channels to a pwm class and set their device type to pwm_channel so >> uevents are sent. >> >> To do this properly, the device names need to change to uniquely >> identify a channel. This change is from pwmN to pwm-(chip->base):N >> >> Signed-off-by: David Hsu <[email protected]> >> Signed-off-by: Greg Kroah-Hartman <[email protected]> >> --- >> Documentation/pwm.txt | 6 ++++-- >> drivers/pwm/sysfs.c | 15 ++++++++++++--- >> 2 files changed, 16 insertions(+), 5 deletions(-) >> >> Note, this patch came from David with his work on a system that has >> dynamic PWM devices and channels, and we needed some way to tell >> userspace what is going on when they are added or removed. If anyone >> knows any other way of doing this that does not involve changing the pwm >> names, please let us know. > > Is it truly PWM channels that dynamically appear and disappear? I'd be > interested in how that's achieved, because there are probably other > issues that will manifest if you do that. Do you have a pointer to the > work that David's been undertaking? Generally some more context on the > use-case would be helpful here.
Only PWM devices are dynamic, the number of channels exposed by devices do not change after they've been added to the system. > > Also I'd prefer if this avoided using chip->base here, because it exists > purely for legacy purposes and is supposed to go away eventually. > > Thierry Would using dev_name(parent) be an acceptable alternative? Thanks, David
