From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [RFE PATCH 2/2] rtc, add write functionality to sysfs Date: Sun, 24 Feb 2013 12:03:01 -0500 Message-ID: <512A47C5.3010500@redhat.com> References: <1360861375-24131-1-git-send-email-prarit@redhat.com> <1360861375-24131-3-git-send-email-prarit@redhat.com> <5127D884.6020701@linaro.org> <5127DB2B.3030700@redhat.com> <5127DDAF.2000403@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alessandro Zummo Cc: John Stultz , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Thomas Gleixner , "x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , Matt Fleming , David Vrabel , Andrew Morton , Andi Kleen , "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org" List-Id: linux-efi@vger.kernel.org On 02/23/2013 06:11 PM, Alessandro Zummo wrote: > On 22/feb/2013, at 22:05, John Stultz wrote: > >> On 02/22/2013 12:55 PM, Prarit Bhargava wrote: >>> >>> On 02/22/2013 03:43 PM, John Stultz wrote: >>>> On 02/14/2013 09:02 AM, Prarit Bhargava wrote: >>>>> /sys/class/rtc/rtcX/date and /sys/class/rtc/rtcX/time currently have >>>>> read-only access. This patch introduces write functionality which will >>>>> set the rtc time. >>>>> >>>>> Usage: echo YYYY-MM-DD > /sys/class/rtc/rtcX/date >>>>> echo HH:MM:SS > /sys/class/rtc/rtcX/time >>>> Why do we want to add a new interface here? >>> John, >>> >>> I'm not adding a new interface. The current date/time interface only handles >>> read and I'm introducing write. >>> >> >> Right, but what benefit does that provide? >> (I'm not saying there isn't any, its just not clear from your patch why this is a good thing.) >> Sorry John, I misunderstood your question. >> Also CC'ing Alessandro for his input. > > I'd like to keep the interfaces as simple as possible but I'm open to improvements if there are good use cases. > AFAICT there is no way for me to "test" or use the write from userspace. hwclock uses the SET_TIME ioctl, which is a different code path AFAICT. I'd like to be at least able to test this stuff when we make changes to it so I think having write functionality for date & time is worthwhile. For me, I'm using these to heavily test ntp and ntpdate over system reboots. OOC, Alessandro, why is the date & time split into two fields? P. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759090Ab3BXRDp (ORCPT ); Sun, 24 Feb 2013 12:03:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:30415 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751628Ab3BXRDn (ORCPT ); Sun, 24 Feb 2013 12:03:43 -0500 Message-ID: <512A47C5.3010500@redhat.com> Date: Sun, 24 Feb 2013 12:03:01 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Thunderbird/3.1.10 MIME-Version: 1.0 To: Alessandro Zummo CC: John Stultz , "linux-kernel@vger.kernel.org" , Thomas Gleixner , "x86@kernel.org" , Matt Fleming , David Vrabel , Andrew Morton , Andi Kleen , "linux-efi@vger.kernel.org" , "rtc-linux@googlegroups.com" Subject: Re: [RFE PATCH 2/2] rtc, add write functionality to sysfs References: <1360861375-24131-1-git-send-email-prarit@redhat.com> <1360861375-24131-3-git-send-email-prarit@redhat.com> <5127D884.6020701@linaro.org> <5127DB2B.3030700@redhat.com> <5127DDAF.2000403@linaro.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/23/2013 06:11 PM, Alessandro Zummo wrote: > On 22/feb/2013, at 22:05, John Stultz wrote: > >> On 02/22/2013 12:55 PM, Prarit Bhargava wrote: >>> >>> On 02/22/2013 03:43 PM, John Stultz wrote: >>>> On 02/14/2013 09:02 AM, Prarit Bhargava wrote: >>>>> /sys/class/rtc/rtcX/date and /sys/class/rtc/rtcX/time currently have >>>>> read-only access. This patch introduces write functionality which will >>>>> set the rtc time. >>>>> >>>>> Usage: echo YYYY-MM-DD > /sys/class/rtc/rtcX/date >>>>> echo HH:MM:SS > /sys/class/rtc/rtcX/time >>>> Why do we want to add a new interface here? >>> John, >>> >>> I'm not adding a new interface. The current date/time interface only handles >>> read and I'm introducing write. >>> >> >> Right, but what benefit does that provide? >> (I'm not saying there isn't any, its just not clear from your patch why this is a good thing.) >> Sorry John, I misunderstood your question. >> Also CC'ing Alessandro for his input. > > I'd like to keep the interfaces as simple as possible but I'm open to improvements if there are good use cases. > AFAICT there is no way for me to "test" or use the write from userspace. hwclock uses the SET_TIME ioctl, which is a different code path AFAICT. I'd like to be at least able to test this stuff when we make changes to it so I think having write functionality for date & time is worthwhile. For me, I'm using these to heavily test ntp and ntpdate over system reboots. OOC, Alessandro, why is the date & time split into two fields? P.