From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=o2.pl header.i=@o2.pl header.b="U+iHv3Hd" Received: from mx-out.tlen.pl (mx-out.tlen.pl [193.222.135.158]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A87210D4 for ; Mon, 27 Nov 2023 12:31:25 -0800 (PST) Received: (wp-smtpd smtp.tlen.pl 29066 invoked from network); 27 Nov 2023 21:31:20 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=o2.pl; s=1024a; t=1701117080; bh=AVLfSEKQHabLjQ2op4Bnsbc4bMus8YV3MiHTkOWOTvE=; h=Subject:To:Cc:From; b=U+iHv3Hd+CuZ2OKDVmzz+RgPnHjEqi2CladEWxSy3bln6TX+CIMBzlyEq/5AXSfvb 0OJI8B/RtbP54v2PcX07GE4wSZxLJMZhwEFnkomcm2o+46bsy6mgTIdcF1DVPEXhDN OYWq5WcfH9vXlaKhKUBgJUgcMPCP68EI+rjxpagY= Received: from aaez25.neoplus.adsl.tpnet.pl (HELO [192.168.1.22]) (mat.jonczyk@o2.pl@[83.4.129.25]) (envelope-sender ) by smtp.tlen.pl (WP-SMTPD) with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP for ; 27 Nov 2023 21:31:20 +0100 Message-ID: Date: Mon, 27 Nov 2023 21:31:16 +0100 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 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, dhaval.giani@gmail.com, Dave Hansen , Borislav Petkov , "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar References: <20231127192553.9734-1-mario.limonciello@amd.com> <20231127192553.9734-4-mario.limonciello@amd.com> From: =?UTF-8?Q?Mateusz_Jo=C5=84czyk?= Autocrypt: addr=mat.jonczyk@o2.pl; keydata= xsFNBFqMDyQBEAC2VYhOvwXdcGfmMs9amNUFjGFgLixeS2C1uYwaC3tYqjgDQNo/qDoPh52f ExoTMJRqx48qvvY/i6iwia7wOTBxbYCBDqGYxDudjtL41ko8AmbGOSkxJww5X/2ZAtFjUJxO QjNESFlRscMfDv5vcCvtH7PaJJob4TBZvKxdL4VCDCgEsmOadTy5hvwv0rjNjohau1y4XfxU DdvOcl6LpWMEezsHGc/PbSHNAKtVht4BZYg66kSEAhs2rOTN6pnWJVd7ErauehrET2xo2JbO 4lAv0nbXmCpPj37ZvURswCeP8PcHoA1QQKWsCnHU2WeVw+XcvR/hmFMI2QnE6V/ObHAb9bzg jxSYVZRAWVsdNakfT7xhkaeHjEQMVRQYBL6bqrJMFFXyh9YDj+MALjyb5hDG3mUcB4Wg7yln DRrda+1EVObfszfBWm2pC9Vz1QUQ4CD88FcmrlC7n2witke3gr38xmiYBzDqi1hRmrSj2WnS RP/s9t+C8M8SweQ2WuoVBLWUvcULYMzwy6mte0aSA8XV6+02a3VuBjP/6Y8yZUd0aZfAHyPi Rf60WVjYNRSeg27lZ9DJmHjSfZNn1FrtZi3W9Ff6bry/SY9D136qXBQxPYxXQfaGDhVeLUVF Q+NIZ6NEjqrLQ07LEvUW2Qzk2q851/IaXZPtP6swx0gqrpjNrwARAQABzSRNYXRldXN6IEpv xYRjenlrIDxtYXQuam9uY3p5a0BvMi5wbD7CwX4EEwECACgFAlqMDyQCGwMFCRLMAwAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEPvWWrhhCv7Gb0MQAJVIpJ1KAOH6WaT8e65xZulI 1jkwGwNp+3bWWc5eLjKUnXtOYpa9oIsUUAqvh/L8MofGtM1V11kSX9dEloyqlqDyNSQk0h52 hZxMsCQyzjGOcBAi0zmWGYB4xu6SXj4LpVpIPW0sogduEOfbC0i7uAIyotHgepQ8RPGmZoXU 9bzFCyqZ8kAqwOoCCx+ccnXtbnlAXQmDb88cIprAU+Elk4k4t7Bpjn2ek4fv35PsvsBdRTq3 ADg8sGuq4KQXhbY53n1tyiab3M88uv6Cv//Ncgx+AqMdXq2AJ7amFsYdvkTC98sx20qk6Cul oHggmCre4MBcDD4S0qDXo5Z9NxVR/e9yUHxGLc5BlNj+FJPO7zwvkmIaMMnMlbydWVke0FSR AzJaEV/NNZKYctw2wYThdXPiz/y7aKd6/sM1jgPlleQhs3tZAIdjPfFjGdeeggv668M7GmKl +SEzpeFQ4b0x64XfLfLXX8GP/ArTuxEfJX4L05/Y9w9AJwXCVEwW4q17v8gNsPyVUVEdIroK cve6cgNNSWoxTaYcATePmkKnrAPqfg+6qFM4TuOWmyzCLQ1YoUZMxH+ddivDQtlKCp6JgGCz c9YCESxVii0vo8TsHdIAjQ/px9KsuYBmOlKnHXKbj6BsE/pkMMKQg/L415dvKzhLm2qVih7I U16IAtK5b7RpzsFNBFqMDyQBEACclVvbzpor4XfU6WLUofqnO3QSTwDuNyoNQaE4GJKEXA+p Bw5/D2ruHhj1Bgs6Qx7G4XL3odzO1xT3Iz6w26ZrxH69hYjeTdT8VW4EoYFvliUvgye2cC01 ltYrMYV1IBXwJqSEAImU0Xb+AItAnHA1NNUUb9wKHvOLrW4Y7Ntoy1tp7Vww2ecAWEIYjcO6 AMoUX8Q6gfVPxVEQv1EpspSwww+x/VlDGEiiYO4Ewm4MMSP4bmxsTmPb/f/K3rv830ZCQ5Ds U0rzUMG2CkyF45qXVWZ974NqZIeVCTE+liCTU7ARX1bN8VlU/yRs/nP2ISO0OAAMBKea7slr mu93to9gXNt3LEt+5aVIQdwEwPcqR09vGvTWdRaEQPqgkOJFyiZ0vYAUTwtITyjYxZWJbKJh JFaHpMds9kZLF9bH45SGb64uZrrE2eXTyI3DSeUS1YvMlJwKGumRTPXIzmVQ5PHiGXr2/9S4 16W9lBDJeHhmcVOsn+04x5KIxHtqAP3mkMjDBYa0A3ksqD84qUBNuEKkZKgibBbs4qT35oXf kgWJtW+JziZf6LYx4WvRa80VDIIYCcQM6TrpsXIJI+su5qpzON1XJQG2iswY8PJ40pkRI9Sm kfTFrHOgiTpwZnI9saWqJh2ABavtnKZ1CtAY2VA8gmEqQeqs2hjdiNHAmRxR2wARAQABwsFl BBgBAgAPBQJajA8kAhsMBQkSzAMAAAoJEPvWWrhhCv7GhpYP/1tH/Kc35OgWu2lsgJxR9Z49 4q+yYAuu11p0aQidL5utMFiemYHvxh/sJ4vMq65uPQXoQ3vo8lu9YR/p8kEt8jbljJusw6xQ iKA1Cc68xtseiKcUrjmN/rk3csbT+Qj2rZwkgod8v9GlKo6BJXMcKGbHb1GJtLF5HyI1q4j/ zfeu7G1gVjGTx8e2OLyuBJp0HlFXWs2vWSMesmZQIBVNyyL9mmDLEwO4ULK2quF6RYtbvg+2 PMyomNAaQB4s1UbXAO87s75hM79iszIzak2am4dEjTx+uYCWpvcw3rRDz7aMs401CphrlMKr WndS5qYcdiS9fvAfu/Jp5KIawpM0tVrojnKWCKHG4UnJIn+RF26+E7bjzE/Q5/NpkMblKD/Y 6LHzJWsnLnL1o7MUARU++ztOl2Upofyuj7BSath0N632+XCTXk9m5yeDCl/UzPbP9brIChuw gF7DbkdscM7fkYzkUVRJM45rKOupy5Z03EtAzuT5Z/If3qJPU0txAJsquDohppFsGHrzn/X2 0nI2LedLnIMUWwLRT4EvdYzsbP6im/7FXps15jaBOreobCaWTWtKtwD2LNI0l9LU9/RF+4Ac gwYu1CerMmdFbSo8ZdnaXlbEHinySUPqKmLHmPgDfxKNhfRDm1jJcGATkHCP80Fww8Ihl8aS TANkZ3QqXNX2 In-Reply-To: <20231127192553.9734-4-mario.limonciello@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-WP-MailID: 1a138dafb272c999ed76f246b5ecae23 X-WP-AV: skaner antywirusowy Poczty o2 X-WP-SPAM: NO 0000000 [sYMB] W dniu 27.11.2023 o 20:25, 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(). > > If UIP timeout is configured by caller to be >=100 ms and a call > takes this long, log a warning. > > Make all callers use 10ms to ensure no functional changes. > > Cc: stable@vger.kernel.org # 6.1.y > Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") > Signed-off-by: Mario Limonciello > --- > v2->v3: > * Logic adjustments > * Clarify warning message > v1->v2: > * Add a warning if 100ms or more > * Add stable and fixes tags [snip] > diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c > index 43a28e82674e..ab077dde397b 100644 > --- a/drivers/rtc/rtc-mc146818-lib.c > +++ b/drivers/rtc/rtc-mc146818-lib.c > @@ -8,26 +8,31 @@ > #include > #endif > > +#define UIP_RECHECK_DELAY 100 /* usec */ > +#define UIP_RECHECK_DELAY_MS (USEC_PER_MSEC / UIP_RECHECK_DELAY) > +#define UIP_RECHECK_TIMEOUT_MS(x) (x / UIP_RECHECK_DELAY_MS) > + > /* > * 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 < UIP_RECHECK_TIMEOUT_MS(timeout); i++) { Sorry, this will not work. UIP_RECHECK_DELAY_MS is 10, so UIP_RECHECK_TIMEOUT_MS(timeout) will be 1 for timeout=10. Should be       for (i = 0; UIP_RECHECK_TIMEOUT_MS(i) < timeout; i++) { With this, for i == 99, UIP_RECHECK_TIMEOUT_MS(i) = 9 for i == 100, UIP_RECHECK_TIMEOUT_MS(i) = 10 and the loop correctly terminates. The macro should probably be renamed UIP_RECHECK_LOOPS_MS as it converts loop count to ms. > 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 +42,7 @@ 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 +61,7 @@ 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; > } > > @@ -72,6 +77,10 @@ bool mc146818_avoid_UIP(void (*callback)(unsigned char seconds, void *param), > } > spin_unlock_irqrestore(&rtc_lock, flags); > > + if (i >= UIP_RECHECK_TIMEOUT_MS(100)) Same, should be: if (UIP_RECHECK_TIMEOUT_MS(i) >= 100) > + pr_warn("Reading current time from RTC took around %d ms\n", > + UIP_RECHECK_TIMEOUT_MS(i)); > + > return true; > } > return false; [snip] Greetings, Mateusz