From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [PATCH 01/10] dt/bindings: Add binding for BCM2835 mailbox driver Date: Thu, 12 Mar 2015 16:23:52 -0700 Message-ID: <87egothkaf.fsf@eliezer.anholt.net> References: <1425329684-23968-1-git-send-email-eric@anholt.net> <1425329684-23968-2-git-send-email-eric@anholt.net> <20150303080550.GF6976@x1> <87vbih98za.fsf@eliezer.anholt.net> <54F66FDD.2040409@wwwdotorg.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Return-path: In-Reply-To: <54F66FDD.2040409-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren , Lee Jones Cc: linux-arm-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jassi Brar , Craig McGeachie , Lubomir Rintel List-Id: devicetree@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Stephen Warren writes: > On 03/03/2015 12:28 PM, Eric Anholt wrote: >> Lee Jones writes: >>=20 >>> On Mon, 02 Mar 2015, Eric Anholt wrote: >>>> +Example: + +mailbox: mailbox@7e00b800 { + compatible =3D=20 >>>> "brcm,bcm2835-mbox"; + reg =3D <0x7e00b880 0x40>; + interrupts =3D=20 >>>> <0 1>; + #mbox-cells =3D <1>; +}; >>>=20 >>> It would be good to see the client examples here as well. >>> Please consider pulling in brcm,bcm2835-mbox-power.txt and=20 >>> brcm,bcm2835-mbox-property.txt. >>=20 >> Oh, so have those two just smashed into this file as one set of=20 >> documentation for everything to do with mailbox on bcm2835? That=20 >> seems good to me. When I was adding the client drivers, the fact=20 >> that the other brcm file was named after the compatible string >> made me generate new files under then new compatible strings, but >> the other drivers already in the tree obviously aren't formatted >> that way. > > The HW mailbox seems like a different process to the upper-layer > protocols/message formats running over the top of it. Sure right now > the Pi has a single firmware, but do all bcm2835-based devices share > the same firmware? Is so, we'd be warranted in lumping the HW and > firmware protocol together, but I rather wonder whether e.g. the > bcm2835-based Roku uses the same firmware protocol? I've confirmed: While their firmware would have been forked from the same source, there's no reason to expect their shipped firmware protocols (like my power domain or property channel drivers use) to match RPi's. The power-domain rework ended up not working out -- it needs the power-domain part of device/base to support throwing -EPROBE_DEFER if the driver hasn't probed yet, unless we're willing to just bake in the power domain driver in static init ordering. Device base maintainers weren't excited about my patch for -EPROBE_DEFER, because then a new DT would mean we start failing to probe the USB driver in an older kernel, which whould be a regression in the case that the user had U-Boot setting up USB for them. Meanwhile, it looks like the thing being done in the firmware for USB is not just a power domain, but also configuration of the USB PHY. This led me to wonder if I could just write native support for the PHY and the power domains instead of asking the firmware to do it, but this is going to take more investigation. As a result, I'm going to shelve my power domain and property channel work for the moment, and just submit the core mailbox support that I feel pretty confident about for now. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBCgAGBQJVAiAIAAoJELXWKTbR/J7oPbUP/2U5Z1i4suC+5eCI8W4t+0AY myKhqUnRveo+beS5jaTVQPvbiyo9Y38Y1Jbjk+J3cDfHXJH4Fyn9efUC1ACfDW4+ VRhjVnLS6yTgHrMYXEIZAE80DIf0Ale/m3EWUXx9Vv+7FTjN13HlPEieaCVETItf TLAZua4PmKdQ1j51VlBTvEoGaO4ShbRA4GsguT6pU/j3cQTDUZOkdICGqGROiop4 W9jcIR46T8FqVVUZ3ggyCv5/TjWSGdbmm5/8dRNBzDpoIzPhJu1IKXQsZG/Q8zl/ QPTw9rcSoJcAyUuSKJqM3/cJnLeS9yf1wJ4odjhZYelybPXhy5a5GqAdckIpm3m/ mcuTkoqj6l8oTgvOqm7f2iyaLcfBLSn9lxM6s4Bk+uTc7d+YRWE8JulFaub4JdC4 T7ATPoe8mbQVhEFUZPSH72Z0WUwsDlrDwmgF/aMoG2q1ghguae2psdXGHera6uzN RHyPXIY3JHWF78w5cv5hVwxYOrPSc/9XGHTbtF446rVL4S20xH7VvOBm1dv1Pz8v xVZGe8oIuJNuhA5A3Evgp6JZJF4uYD9NPlZHnFCVgRHhOO1XexQmtG8sX93FzoQG y7JJIlIrkQCqWsRL+0/1Exeeg6Uwps49VWI/R6Zs+51GZKbDP4rhYDzjXz+zZvv0 nFojNukxJdRiXTltlgEy =cP62 -----END PGP SIGNATURE----- --=-=-=-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html