From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [Gta04-owner] [PATCH 3/3] tty/slaves: add a driver to power on/off UART attached devices. Date: Thu, 26 Mar 2015 06:56:39 +0100 Message-ID: <20150326055639.GA20912@amd> References: <20150318055831.21025.33670.stgit@notabene.brown> <20150320195451.146a7915@notabene.brown> <14FB51CF-9568-4BF4-B917-2C019D992FDB@goldelico.com> <20150321103122.23603014@notabene.brown> <20150325014543.GA967@earth> <6B657A35-68BD-45F6-BD55-A3D6AC1055C8@goldelico.com> <20150325205344.GD381@amd> <1F3B5E32-1330-457C-AE25-791319293C38@goldelico.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1F3B5E32-1330-457C-AE25-791319293C38-xXXSsgcRVICgSpxsJD1C4w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Dr. H. Nikolaus Schaller" Cc: Sebastian Reichel , NeilBrown , List for communicating with real GTA04 owners , Mark Rutland , One Thousand Gnomes , Peter Hurley , Arnd Bergmann , Greg Kroah-Hartman , Grant Likely , Jiri Slaby , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lkml List-Id: devicetree@vger.kernel.org Hi! > >>> Main reason is, that I would need to go > >>> through the UART to =E2=80=9Ccommunicate" with the w2sg0004. > >>=20 > >> You can always "communicate=E2=80=9D through the UART. Even withou= t DT. As long as > >> the connected chip is powered up by any means (could be some fixed= -regulator > >> or hard wired). > >=20 > > But you don't know "how" to communicate through the uart. >=20 > Maybe we are talking using different assumptions. As long as you have= a user space > gpsd daemon that talks to the gps chip the kernel simply has to trans= parently (except > line disciplines) pass the data to the uart. =46orget userspace, some other operating system (or future linux) may want to put gps handling into the kernel. (To hide differences between different GPSes). > > Because we want the phone to boot knowing "I have a bluetooth" or "= I > > have a GPS", as it would if it was connected using USB, and not hav= ing > > user figure out what commands he needs to do to enable reasonable > > hardware support (and getting it wrong, because you need to specify > > _many_ critical parameters to hciattach). >=20 > Yes, this is indeed something I also would like to see for the GTA04 = (and other) > devices. >=20 > So the reason is that some kernel driver wants to use the tty/uart to= communicate > directly with the chip. This is very similar to a gpio that some driv= er wants to use. >=20 > Thus please consider the >=20 > / { > bt { > compatible =3D "vendor,product=E2=80=9C; > uart =3D <&uart1>; > enable =3D <&gpio17 34 0>; > }; > }; Would work, too, but I and everyone knows that subnode is better, easier solution. > approach. >=20 > And if you want to hide uart1 from the user-space, that should be a p= roperty > of the uart1 node (whereever it is defined). Sorry? That would be one heck of layering violation. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses= /blog.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html