On 01/04/2013 06:33 PM, Stephen Warren wrote: > On 01/03/2013 04:52 AM, Timur wrote: > ... >> maybe you remember this brief conversation in December. I found the root >> cause of the reported issue (tegra specific) and I can provide a patch. >> The outcome is stable, externally powered USB host mode for Nexus 7. > Isn't USB host mode by definition internally powered, and USB device > mode by definition externally powered? An externally powered USB host > mode sounds quite non-standard. If you allow that mode, how does the > system know whether it should be a host or a device when external power > is applied; it sounds like this new mode completely breaks the ability > to connect the tablet to a PC and use it for Android application > development, or MTP (Media Transfer Protocol) to download pictures/movies. What I am proposing does not result in any loss of original functionality (ADB, MTP, etc.). Also, the described added functionality is fully standard when I look at it. No typical PC needs to switch to battery power, only to connect USB slave devices. You can operate a Nexus 7 on external power. But in order to connect USB slave devices, you *have* to switch to internal battery. Not being able to run USB host mode at all, while using external power, is a serious shortcoming. One that is only caused by the installed kernel. In December, I was having this last difficulty: preserving USB host operations through LP0 phases. But this problem has been solved. Really wanted to clarify this. > >> Do you happen to know anyone responsible for the Ubuntu Nexus7 kernel? I >> would like to contribute the fix, as I think it would be beneficial to >> that implementation. > Sorry, I don't know what kernel they're using; the best place to ask > would be the Ubuntu project itself. No, I did not ask what kernel they are using. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
