Messages in this thread | | | From | David Brownell <> | Subject | Re: [patch/rfc 2.6.25-git v2] gpio: sysfs interface | Date | Wed, 30 Apr 2008 19:12:55 -0700 |
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> > This is > > very helpful for people connecting something to the interface to know they > > have the write gpio lines connected. What's the point of allowing > > one to label gpio lines if it's not going to be easy to see? > > That label was always just supposed to be a debugging aid, i.e. > something to show up in debugfs. This is used to reduce D footprint. > Maybe if the labels are being stored anyway they can be made available > through sysfs as well as debugfs?
They could be; I've had code to do it. It never stays in very long, because for a pure userspace interace it can't be helpful unless userspace makes the labels: the labels displayed otherwise just reuse the same constant.
For a "kernel cooperates with userspace" model that might be more useful. And I've certainly found the debugfs info hard to interpret without such labels!! But Trent has said he doesn't see anyone modifying enough code to adopt such a "cooperates" model. Which is why this particular side-argument seems like a waste of time to me: even he has not proposed the key change his argument depends on.
The original control file syntax I thought about was
export NN mode label
where it would gpio_request(NN, "label") and then set the direction (and maybe value) according to "mode". But that was just a PITA to cope with ... so it's now been trimmed down to just "NN" (and "-NN").
- Dave
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