On Thu, Feb 18, 2016 at 10:21:48AM +0100, Oliver Neukum wrote: > On Thu, 2016-02-18 at 10:47 +0200, Heikki Krogerus wrote: > > Hi, > > > The modes that can actually be selected have to be supported by both > > the connector and the partner, and this is where I'm putting the ball > > on the userspace at the moment. I'm not offering a list of > > "possible_alternate_modes" where I list the combination, but instead > > expect the userspace to be figure out that on it's own. > > > > Do you think we should add "possible_alternate_modes" file? > > No, what do we answer to the DFP if we recieve "Discover SVIDs"? > I don't think that we always should answer with all we physically > can. If, for example, the hardware could do Thunderbolt, but the OS > is not prepared to handle it, we shouldn't offer it. So this is > a policy decision to be made in user space. Hence we need > an API to tell it to the kernel. OK. Makes sense. > > P.S. That reminds me, here's my current draft for the > > Documentation/ABI/. Could you take a look? > > OK > > Here are my comments: > > What: /sys/class/type-c/usbcN/connected > > Connection status of the USB Type-C connector usbcN. "yes" when > connected, otherwise "no". > > Unnecessarily wordy. 0 and 1 would do That works for me. > What: /sys/class/type-c/usbcN/current_data_role > > Again, 0 and 1 would do I disagree with this one. What would 0 mean and what would 1? It would require us to make an agreement about the "index" of the role, which creates a small risk of somebody getting it wrong, but for what purpose? Why couldn't it be human readable "host" or "device" so there is never no confusion about it. > What: /sys/class/type-c/usbcN/partner_alternate_modes > > You should say in which number base the values are given. > > What: /sys/class/type-c/usbcN/partner_type > > That could be combined with "connected" Hmm, so in practice getting rid of "connected" completely.. I guess it's OK. > What: /sys/class/type-c/usbcN/supported_data_roles > > A connector can be both. How is that expressed? "host, device". > What: /sys/class/type-c/usbcN/supported_power_roles > > Again, what if it can do both? "source, sink". So these last two are now listing the values that can be entered to the current_data_role and current_power_role. Thanks, -- heikki -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
