On Mon, Jan 23, 2017 at 04:44:23PM +0200, Felipe Balbi wrote:
>
> Hi,
>
> Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> writes:
> > +static void typec_report_identity(struct device *dev)
> > +{
> > + sysfs_notify(&dev->kobj, "identity", "id_header");
> > + sysfs_notify(&dev->kobj, "identity", "cert_stat");
> > + sysfs_notify(&dev->kobj, "identity", "product");
>
> if you sysfs_notify() all three everytime this might cause issues for
> userspace pollers. What will happen is that you're gonna change
> e.g. id_header and threads polling id_header, cert_stat and product will
> be notified of what's supposed to be new data. Maybe this should know
> what it's notifying and only notify what actually changed. Seems like
> just passing one extra char * argument is enough:
>
> static void typec_report_identity(struct device *dev, const char *prop)
> {
> sysfs_notify(&dev->kobj, "identity", prop);
> }
>
I must admit that I am kind of lost here. In practice all three values are
provided by the PD protocol in a single message, meaning they are all updated
at the same time. The result of this code is that I have to call the function
three times, each time providing what I think should be a class-internal string
as parameter (the low level code should not really be concerned about the
sysfs attribute names). What exactly are we gaining from this ?
Guenter
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