From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sherman Yin Subject: Re: [PATCH v3 4/6] pinctrl: Add pinctrl binding for Broadcom Capri SoCs Date: Tue, 17 Dec 2013 18:02:07 -0800 Message-ID: <52B1021F.2010708@broadcom.com> References: <1381174108-25168-1-git-send-email-syin@broadcom.com> <1386787041-6035-1-git-send-email-syin@broadcom.com> <1386787041-6035-5-git-send-email-syin@broadcom.com> <52ABB150.1030702@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Linus Walleij Cc: Rob Herring , =?ISO-8859-1?Q?Heiko_St=FCbn?= =?ISO-8859-1?Q?er?= , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Rob Landley , Christian Daudt , Russell King , Grant Likely , Matt Porter , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , bcm-kernel-feedback-list , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On 13-12-16 05:17 AM, Linus Walleij wrote: > On Sat, Dec 14, 2013 at 2:16 AM, Sherman Yin wrote: > >>>> +- bias-pull-up: Integer. Pull up strength in Ohm: >>>> + 1: 1.2 kOhm >>>> + 2: 1.8 kOhm >>>> + 3: 720 Ohm >>>> + 4: 2.7 kOhm >>>> + 5: 831 Ohm >>>> + 6: 1.08 kOhm >>>> + 7: 568 Ohm >>> >>> >>> Please do not use these custom enumerators 1 thru 7. >>> Instead say that the argument is given in ohms, so for >>> example: >>> >>> bias-pull-up = <12000>; >>> >>> Then translate this into the proper enumerator in your >>> driver instead. >> >> Ok. The 3 bits in this enumeration correspond to enabling the 3 pull up Rs >> (1.2k, 1.8k, 2.7k) in parallel, so the enum kind of make sense. But sure I >> can change it to actual ohms and will error out in the driver if specified >> value is not one of the 7. > > Aha, that's how they do it :-) > > Please write this in a comment in the driver because it makes > it a lot easier to understand what is going on, and e.g. how to > fuzz an apropriate resistance. Yes, I plan to explain where those odd numbers come from in this file. > Can you tell me something about how such resistors are produced > in silicon? Sorry I'm not quite sure. I only know a little bit of the circuitry down to the schematic level... Regards, Sherman -- 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