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 8CC5CC54E76 for ; Sat, 18 Nov 2023 19:07:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230206AbjKRTHO (ORCPT ); Sat, 18 Nov 2023 14:07:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230232AbjKRTHM (ORCPT ); Sat, 18 Nov 2023 14:07:12 -0500 Received: from mx-out.tlen.pl (mx-out.tlen.pl [193.222.135.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27FCED5F for ; Sat, 18 Nov 2023 11:07:05 -0800 (PST) Received: (wp-smtpd smtp.tlen.pl 29537 invoked from network); 18 Nov 2023 20:07:02 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1700334422; bh=ah97aCbN24GtUBFT8VSBvxF84jY96VzFBfOL/rbwUPw=; h=Subject:To:Cc:From; b=QIMdCusO1tTtUrw7L3tTLKOgB5VfiROd/ZmFSaxCo+kSCGyovbm8+BVYYg5ae7cyz zttG8pedzbbaQlkKNPJCW3+N/cWFo98RfdkHCJTc1rkZj0LOjh6UGdmpSfUgRUcIdd YFB+/oLZEHpi/kb4IAA4uMjOmXTw8UThtDtrX+3A= Received: from aafl106.neoplus.adsl.tpnet.pl (HELO [192.168.1.22]) (mat.jonczyk@o2.pl@[83.4.141.106]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP for ; 18 Nov 2023 20:07:02 +0100 Message-ID: <9a34ad89-6263-4cda-b938-348bdf62e155@o2.pl> Date: Sat, 18 Nov 2023 20:06:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] rtc: Add support for configuring the UIP timeout for RTC reads Content-Language: en-GB To: Mario Limonciello , Alessandro Zummo , Alexandre Belloni Cc: "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" , open list , linux-pm@vger.kernel.org, tobrohl@gmail.com, aalsing@gmail.com, Dhaval.Giani@amd.com, xmb8dsv4@gmail.com, x86@kernel.org References: <20231117063220.65093-1-mario.limonciello@amd.com> <20231117063220.65093-4-mario.limonciello@amd.com> From: =?UTF-8?Q?Mateusz_Jo=C5=84czyk?= Autocrypt: addr=mat.jonczyk@o2.pl; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-WP-MailID: 7ac0a0c6de035ddcdf3814c62d506835 X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [waP0] Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hello, W dniu 17.11.2023 o 07:32, Mario Limonciello pisze: > The UIP timeout is hardcoded to 10ms for all RTC reads, but in some > contexts this might not be enough time. Add a timeout parameter to > mc146818_get_time() and mc146818_get_time_callback(). > Make all callers use 10ms to ensure no functional changes. > > Signed-off-by: Mario Limonciello Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") If you would like to Cc: stable this patch, commit d2a632a8a117 ("rtc: mc146818-lib: reduce RTC_UIP polling period") is a prerequisite. > --- > arch/alpha/kernel/rtc.c | 2 +- > arch/x86/kernel/hpet.c | 2 +- > arch/x86/kernel/rtc.c | 2 +- > drivers/base/power/trace.c | 2 +- > drivers/rtc/rtc-cmos.c | 6 +++--- > drivers/rtc/rtc-mc146818-lib.c | 31 +++++++++++++++++++++++-------- > include/linux/mc146818rtc.h | 3 ++- > 7 files changed, 32 insertions(+), 16 deletions(-) > [snip] > --- a/drivers/rtc/rtc-mc146818-lib.c > +++ b/drivers/rtc/rtc-mc146818-lib.c > @@ -8,26 +8,29 @@ > #include > #endif > > +#define UIP_RECHECK_DELAY 100 /* usec */ > + > /* > * Execute a function while the UIP (Update-in-progress) bit of the RTC is > - * unset. > + * unset. The timeout is configurable by the caller in ms. > * > * Warning: callback may be executed more then once. > */ > bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), > + int timeout, > void *param) > { > int i; > unsigned long flags; > unsigned char seconds; > > - for (i = 0; i < 100; i++) { > + for (i = 0; i < USEC_PER_MSEC / UIP_RECHECK_DELAY * timeout; i++) { > spin_lock_irqsave(&rtc_lock, flags); > > /* > * Check whether there is an update in progress during which the > * readout is unspecified. The maximum update time is ~2ms. Poll > - * every 100 usec for completion. > + * for completion. > * > * Store the second value before checking UIP so a long lasting > * NMI which happens to hit after the UIP check cannot make > @@ -37,7 +40,7 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), > > if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { > spin_unlock_irqrestore(&rtc_lock, flags); > - udelay(100); > + udelay(UIP_RECHECK_DELAY); > continue; > } > > @@ -56,7 +59,7 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), > */ > if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { > spin_unlock_irqrestore(&rtc_lock, flags); > - udelay(100); > + udelay(UIP_RECHECK_DELAY); > continue; > } > I think that when reading the RTC is not finished in 100ms or so (irrespective of the timeout parameter), the code should log a warning / an error message. Greetings, Mateusz