From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5705C04E69 for ; Wed, 16 Aug 2023 16:20:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344640AbjHPQTc (ORCPT ); Wed, 16 Aug 2023 12:19:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344671AbjHPQTN (ORCPT ); Wed, 16 Aug 2023 12:19:13 -0400 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::224]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B4E12712; Wed, 16 Aug 2023 09:19:08 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 2582BE0006; Wed, 16 Aug 2023 16:19:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1692202746; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SSRdwSp0CkIkHnz/RJq/71YFRiVLOTwdYIHwE8GDwYE=; b=MhmrIo4hFHDnkrdlAPBxiDax+PEGnvkKjdwa5LdSpKEs0s5RSzKcDUKo3c1oVuTF82MFec 2E2tYVj/6iGqxGdjOIUnAMNkm8ydiIOqaI7Ttn9BxxqFnJr/2iBpWpVKczuaZOlKD9eeNi zqgDdcHEVSBZeE9Jyhc451cLDoELcmfRDA5jL0+SSfMbX1/NnNenMrTulHH+cMjcmTmFjL 6P4NgY8A0Wc8AofKQ1z6sPVyHGIt/ndOoKxXUs9376Q95WaTeNYkFFDeXj2tfpGLrETJ11 VsB4RxfZ1AqPvojOwCavitPcxGGGdnq67+2IMs30fCFxeEgfY3VuCsLyy0L04w== Date: Wed, 16 Aug 2023 18:19:05 +0200 From: Alexandre Belloni To: Guenter Roeck Cc: Alessandro Zummo , Benson Leung , Miquel Raynal , Thomas Gleixner , John Stultz , Stephen Boyd , linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, Brian Norris Subject: Re: [PATCH 1/7] rtc: Add support for limited alarm timer offsets Message-ID: <202308161619050943672a@mail.local> References: <20230816133936.2150294-1-linux@roeck-us.net> <20230816133936.2150294-2-linux@roeck-us.net> <202308161457306eecdefb@mail.local> <9b6c7803-f258-472d-9983-530e42e80816@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9b6c7803-f258-472d-9983-530e42e80816@roeck-us.net> X-GND-Sasl: alexandre.belloni@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/08/2023 08:24:39-0700, Guenter Roeck wrote: > On Wed, Aug 16, 2023 at 04:57:30PM +0200, Alexandre Belloni wrote: > > On 16/08/2023 06:39:30-0700, Guenter Roeck wrote: > > > Some alarm timers are based on time offsets, not on absolute times. > > > In some situations, the amount of time that can be scheduled in the > > > future is limited. This may result in a refusal to suspend the system, > > > causing substantial battery drain. > > > > > > Some RTC alarm drivers remedy the situation by setting the alarm time > > > to the maximum supported time if a request for an out-of-range timeout > > > is made. This is not really desirable since it may result in unexpected > > > early wakeups. > > > > > > To reduce the impact of this problem, let RTC drivers report the maximum > > > supported alarm timer offset. The code setting alarm timers can then > > > decide if it wants to reject setting alarm timers to a larger value, if it > > > wants to implement recurring alarms until the actually requested alarm > > > time is met, or if it wants to accept the limited alarm time. > > > > > > Only introduce the necessary variable into struct rtc_device. > > > Code to set and use the variable will follow with subsequent patches. > > > > > > Cc: Brian Norris > > > Signed-off-by: Guenter Roeck > > > --- > > > include/linux/rtc.h | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/include/linux/rtc.h b/include/linux/rtc.h > > > index 1fd9c6a21ebe..b6d000ab1e5e 100644 > > > --- a/include/linux/rtc.h > > > +++ b/include/linux/rtc.h > > > @@ -146,6 +146,7 @@ struct rtc_device { > > > > > > time64_t range_min; > > > timeu64_t range_max; > > > + timeu64_t range_max_offset; > > > > While range_min and range_max are for the wall clock time, I would > > prefer using a name that would clearly mark this as an alarm related > > variable. > > Sure, no problem. Do you have a suggestion ? alarm_range_max or > alarm_range_max_offset, maybe ? I'd also be happy to use some other > term for 'offset' if you have a suggestion. I don't really know, what about alarm_offset_max? This is the maximum value of the offset for the alarm to the current time. -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com