From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 1/5] ptp: Added a brand new class driver for ptp clocks. Date: Fri, 27 Aug 2010 14:03:41 +0200 Message-ID: <201008271403.41949.arnd@arndb.de> References: <1282594899.3111.358.camel@localhost.localdomain> <20100827110855.GA11657@riccoc20.at.omicron.at> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100827110855.GA11657-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Richard Cochran Cc: Rodolfo Giometti , john stultz , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Krzysztof Halasa List-Id: devicetree@vger.kernel.org On Friday 27 August 2010, Richard Cochran wrote: > On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote: > > On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote: > > > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote: > > > > Have you considered passing a struct timex instead of ppb and ts? > > > > > > Yes, but the timex is not suitable, IMHO. > > > > Could you expand on this? > > We need to able to specify that the call is for a PTP clock. We could > add that to the modes flag, like this: > > /*timex.h*/ > #define ADJ_PTP_0 0x10000 > #define ADJ_PTP_1 0x20000 > #define ADJ_PTP_2 0x30000 > #define ADJ_PTP_3 0x40000 > > I can live with this, if everyone else can, too. My suggestion was actually to have a new syscall with the existing structure, and pass a clockid_t value to it, similar to your sys_clock_adjtime(), not change the actual sys_adjtime syscall. > > Could we not add a adjustment mode ADJ_SETOFFSET or something that would > > provide the instantaneous offset correction? > > Yes, but we would also need to add a struct timespec to the struct > timex, in order to get nanosecond resolution. I think it would be > possible to do in the padding at the end? Yes, that's exactly what the padding is for. Instead of timespec, you can probably have a extra values for replacing the existing ppm values with ppb values. Arnd