From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Date: Thu, 02 Aug 2012 08:45:41 +0000 Subject: Re: [RFC][PATCH v3 1/3] runtime interpreted power sequences Message-Id: <20120802084541.GA15042@avionic-0098.adnet.avionic-design.de> MIME-Version: 1 Content-Type: multipart/mixed; boundary="DocE+STaALJfprDB" List-Id: References: <1343390750-3642-1-git-send-email-acourbot@nvidia.com> <1343390750-3642-2-git-send-email-acourbot@nvidia.com> <50170EA0.1010408@wwwdotorg.org> <501A338D.7080105@nvidia.com> <20120802082157.GA14866@avionic-0098.adnet.avionic-design.de> <501A3A00.7070207@nvidia.com> In-Reply-To: <501A3A00.7070207@nvidia.com> To: Alex Courbot Cc: Stephen Warren , Stephen Warren , Simon Glass , Grant Likely , Rob Herring , Greg Kroah-Hartman , Mark Brown , Arnd Bergmann , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fbdev@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" --DocE+STaALJfprDB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 02, 2012 at 05:27:44PM +0900, Alex Courbot wrote: > On Thu 02 Aug 2012 05:21:57 PM JST, Thierry Reding wrote: > >* PGP Signed by an unknown key > > > >On Thu, Aug 02, 2012 at 05:00:13PM +0900, Alex Courbot wrote: > >>On 07/31/2012 07:45 AM, Stephen Warren wrote: > >>>Oh I see. That's a little confusing. Why not just reference the releva= nt > >>>resources directly in each step; something more like: > >>> > >>> gpio@1 { > >>> action =3D "enable-gpio"; > >>> gpio =3D <&gpio 1 0>; > >>> }; > >>> > >>>I guess that might make parsing/building a little harder, since you'd > >>>have to detect when you'd already done gpio_request() on a given GPIO > >>>and not repeat it or something like that, but to me this makes the DT a > >>>lot easier to comprehend. > >> > >>I tried to move towards having the phandles directly in the > >>sequences themselves - that reminded me why I did not do that in the > >>first place. Let's say we have a sequence like this (reg property > >>omitted on purpose): > >> > >> power-on-sequence { > >> step@0 { > >> regulator =3D <&backlight_reg>; > >> enable; > >> }; > >> step@1 { > >> delay =3D <10000>; > >> }; > >> step@2 { > >> pwm =3D <&pwm 2 5000000>; > >> enable; > >> }; > >> step@3 { > >> gpio =3D <&gpio 28 0>; > >> enable; > >> }; > >> }; > >> > >>The problem is, how do we turn these phandles into the resource of > >>interest. The type of the resource can be infered by the name of the > >>property. The hard part is resolving the resource from the phandle - > >>it seems like the API just does not allow to do this. GPIO has > >>of_get_named_gpio, but AFAIK there are no equivalent for regulator > >>consumer and PWM: the only way to use the DT with them is through > >>get_regulator and get_pwm which work at the device level. > >> > >>Or is there a way that I overlooked? > > > >No, you are right. Perhaps we should add exported functions that do the > >equivalent of of_pwm_request() or the regulator_dev_lookup() and > >of_get_regulator() pair. >=20 > How would that be looked with respect to "good DT practices"? I can > somehow understand the wish to restrain DT access to these functions > that integrate well with current workflows. Aren't we going to be > frowned upon if we make more low-level functions public? Yes, I think that's exactly what will happen. Thierry --DocE+STaALJfprDB Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQGj41AAoJEN0jrNd/PrOhmDwQAMEvzOjcnqnUhkvHRWK3SvID 9dVc3dGgPm3A+8b2HCUDkfkaaMTZyRr2iOM3gM33T6zXi821tdYibBOyPyOT1Ckj PmuOaCG1NW8duDvbLnqAd5D58l9mVDJk2j3CNVF4XCiC+Ul+9qNLu3RngFf+t0z7 U8Q1Kq2tP51LPxYjK67IgFpRdQvzdq8XQA2jXlHSBkSmMqIt61dWcAvNqJvlqpa9 bFg18L3zQG1YzFrOXvfRKIX4hTblPkvBoxmrbn9j6oR/mAOJLNu8tpWtHs3SocnB tCH1NowSgGjiLeFLXTQxnfD421YsPZhyjWi+WXvsRnMLIaM+IqRtm/jYcfu2Os5M aiueERjqaGOnAq7k4gWPGzbhZ2a2fiuw26XUr3fIi2Ae+HnP8FYJLWyW7zAXOmYM zyv98RRdkP3LscUlZOzWIglpwQgOq/NSySFS/WyeGtkvJYxZ+CQg+Q6pomwAiQsC r86+koAUrtTHl4sO/FosDT9Q3/HCItF7j3Dw85PhszzZiIdg0PnW7XrQKsQZknch MqbxNzOrKUf6+Nd1npjmZSkTdpLvpSm0rD+sO3ET4YJxhnQF1sFvRhyW62q5XyWM Yp9yGbFgmLr8CKrBmlpkbaTqwS9372ZFTYsxb7ATqhGx+KHL2EPxLDXX/TFWCpeR ZfG5wD9BuY7YT0BzesTT =tJ1V -----END PGP SIGNATURE----- --DocE+STaALJfprDB--