From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Tue, 12 May 2015 16:57:17 +0200 Subject: [PATCH 1/2] ARM: dts: sun9i: cubieboard4: Enable USB support In-Reply-To: References: <1431017037-28331-1-git-send-email-wens@csie.org> <1431017037-28331-2-git-send-email-wens@csie.org> <20150508074616.GP11057@lukather> <20150508114040.GR11057@lukather> Message-ID: <20150512145717.GN10961@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, May 11, 2015 at 04:26:58PM +0800, Chen-Yu Tsai wrote: > >> >> +&usbphy1 { > >> >> + phy-supply = <®_usb1_vbus>; > >> >> + status = "okay"; > >> >> +}; > >> >> + > >> >> +/* > >> >> + * Unfortunately reg_usb1_vbus also powers one of the ports from usb3's hub. > >> >> + * One should always make sure both regulators are enabled and working for > >> >> + * all USB ports to have power. > >> >> + */ > >> > > >> > Can't we just provide the two regulators, and enable both of them so > >> > that we know that we always have the needed regulators enabled, > >> > disregarding which USB port is used? > >> > >> Would setting "always-on" for both regulators work for you? > >> Or maybe just the one that's used by both USB hosts? > > > > I was more thinking of giving to the phy an additional regulator, so > > that it would enable both the regulators needed to power up all ports. > > That would require adding back all the regulator-related code I > removed from the phy driver before it was merged. (sigh) It's not > like the regulator bindings takes a list. Yeah, but maybe we can just add an optional device-supply property or something like that to power up the devices connected on the bus. > I see this as more of a hardware design flaw, and we should label > it as such. This can be seen as one, and we can debate it for some time I guess, but if the hardware guys were not making crazy stuff like that, we would run out of work pretty quickly :) What we really need to do is find a proper and reliable way to handle this case. Whether we declare it as a flaw or not is a separate debate. > And it might still work for self-powered devices even if VBUS is > off. The USB hub chip is always on. That still leaves a significant amount of devices out and non functional, especially very standard devices like USB keys, keyboards or headsets that you would expect to just work. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: