On Thu, Jan 20, 2022 at 5:20 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Thu, Jan 20, 2022 at 03:29:38PM +0530, Rajaram Regupathy wrote: > > On Wed, Jan 19, 2022 at 1:58 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > On Tue, Jan 18, 2022 at 11:16:28AM -0800, Benson Leung wrote: > > > > Hi Greg, > > > > > > > > On Tue, Jan 18, 2022 at 07:33:39PM +0100, Greg KH wrote: > > > > > On Tue, Jan 18, 2022 at 10:01:02PM +0530, Rajaram Regupathy wrote: > > > > > > > Again, why does this have to be a library? > > > > > > > > > > > > > The aim of having a library is to abstract application(s) from OS, > > > > > > platform, PD Controller or Embedded Controller protocols ambiguities > > > > > > and provide common methods. The methods will be similar/closer to UCSI > > > > > > standard. > > > > > > > > > > What methods are needed by an operating system that your library is > > > > > going to provide? How will it be done in a unified way that the current > > > > > user/kernel api isn't providing already today? > > > > > > > > > > > > > A unified libtypec would be useful because the USB Type-C and USB PD > > > > specifications are evolving, and continue to change. Spec changes affect the > > > > decoding of the objects that are exposed by the connector class (the existing > > > > API), and we are at a point where if we left it as-is, you'd have multiple > > > > userspace implementations that would have to independently be updated and > > > > fixed every time there's a new USB PD spec revision or version update. > > > > > > > > Just as a concrete example, Jameson (jthies@xxxxxxxxxx), who works on my team, > > > > recently put together a little helper utility to decode the typec connector > > > > class in order to print it to our feedback report collector. This was all > > > > done before libtypec: > > > > > > > > https://chromium.googlesource.com/chromiumos/platform2/+/749621a6288cc5e80b31a9e6050437a419209fb9/debugd/src/helpers/typec_connector_class_helper.cc > > > > > > > > A problem we ran into almost immediately was that the utility was based on > > > > the most recent USB PD specification documents (USB PD R2.0 and USB PD R3.1), > > > > and had definitions on how to decode PD 2.0 and PD 3.1 objects that it would > > > > read from the typec connector class, however, it was missing definitions for > > > > USB PD R3.0 (a spec revision which is not obvious how to find in USB-IF's > > > > document archive). > > > > > > > > So, we added it: https://chromium.googlesource.com/chromiumos/platform2/+/eb1efefc187feab1182a7680f42fcec6bb14c618 > > > > > > > > Now, every other hypothetical type-c connector class user application or daemon > > > > could potentially make this mistake, and would have to duplicate the work > > > > to fix it. > > > > > > > > If we had libtypec, it would be the unified place to make such a change, and > > > > we'd reduce the burden of new typec apps from having to do all this decode > > > > in the future. > > > > > > Ok, that's fine, but please work to create a library that can handle > > > such changes in non-breaking ways. The first version of this library > > > does not look like it would do that at all as it is exporting way too > > > many things in a "public" interface. > > > > - Fixed compile error caused due to new version of compiler > > - Fixed license details. > > The license details are still quite vague. Please try to put proper > SPDX license identifiers on the individual files so that they are not > vague at all. What you have here will prevent people from being able to > use this code until it is cleaned up, sorry. I have updated license details. It is aligned and made compatible with similar usb frameworks. > > > The library provides interfaces very similar/same as the UCSI standard > > from USB.org. > > What do you mean by this? Exposing raw device structures? Or something > else? No raw device. library reconstructs "data" from interfaces provided by the platforms and makes it available in a standard(UCSI) way to applications. I definitely agree and will keep in mind your guidance of not exporting way too many things in a "public" interface. > > > Additionally the library uses what is available in the existing > > framework and acts as a wrapper between > > lower layers and the applications and not a self reliant entity. > > Could you please help better understand your concern ? > > How can this be used? Few possible usages : 1) Informational utilities like lstype 2) Analyzing Utilities - With usb-c products in different versions, vendors and e-cables usb-c port may not work as intended. this utility shall check usb-c port's operation and report/notify. 3) Test Utilities - Test tools similar to UCSIControl.exe 4) Policy Managers: like https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/typecd/README.md etc.. > > How about adding support for this with lsusb as an example to show how > it might be incorporated. Or better yet, what about adding this to > libusb so that all platforms will work. That is, if this is even > relevant for userspace USB access, which I still can't figure out if it > is or not... IMHO, I believe usb-c is not usb and hence integrating usb-c operations with usb utilities or libraries is not a modular approach. (usbcore vs typec). Having said that if it would be good to integrate lstypec with lsusb as you recommended, would be happy to push patches to lsusb > > Anyway, the license stuff should be fixed up first. If you have an > employer, please work with them to get this right as they all have legal > training for this type of thing. If you do not have an employer, I > recommend taking the free LF online course that helps to describe > licenses and copyrights and how to use them. > > thanks, > > greg k-h
