From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Kulhavy Subject: Re: [PATCH 1/5] dt/bindings: Add binding for the DA8xx MUSB driver Date: Tue, 16 Feb 2016 18:14:30 +0100 Message-ID: <56C358F6.6010008@barix.com> References: <1455188466-10879-1-git-send-email-petr@barix.com> <20160212162110.GA21833@rob-hp-laptop> <56BE1531.8060800@barix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56BE1531.8060800-Qh/3xLP0EvwAvxtiuMwx3w@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rob Herring Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org List-Id: devicetree@vger.kernel.org Hello Rob, is there any follow-up on this one? Thanks Petr On 12.02.2016 18:24, Petr Kulhavy wrote: > > On 12.02.2016 17:21, Rob Herring wrote: >> On Thu, Feb 11, 2016 at 12:01:06PM +0100, Petr Kulhavy wrote: >>> + - mentor,power : Specifies the maximum current in milliamperes the >>> controller can >>> + supply in host mode. >> Still a no for me. Looks like this just sets hcd->power_budget. This >> property may not be a regulator, but ultimately the value depends on >> some regulator supplying Vbus. Also, given this has nothing to do with >> MUSB h/w, however this is described should be generic. > > I understand your point that the description should be generic. > However the USB 2.0 specification does not define any relation between > the bMaxPower provided by the device and the actual power control. > As far as I understand the value just serves the purpose to raise a > flag to the user if the attached device would draw too much power, and > not to enable it at all. > Further, the value used by the protocol is not necessarily related to > the real current that can be supported. The maximum current supported > by the protocol is 510mA. > > For instance on my development board the real maximum current is > limited only by the mains power-supply used. > So it cannot even be modelled in the DT as a regulator because the > power-supply is not part of the HW and > everybody can take a different one. > > So defining a regulator just to store this arbitrary USB 2.0 value is > a bit overkill for me. > > Regards > Petr -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html