From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15117337BB5; Fri, 20 Mar 2026 19:26:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774034765; cv=none; b=foo6QD9I0tQT6lUjqX+4QpfiiRb7sPgnDqPBrx6XxeAs2JCwnIMROCexAdDN3tIpTdzftgIqAvO5JQjhiUiab62R8tPAsrihUQKwCYXCbxl2cvPisDXvEoWHStr9EyntL5fBDIy9rs8lSLINhnr/oaas31KldOHyMt3zSm6ESGw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774034765; c=relaxed/simple; bh=yJiC1Pk7ovdXcihEau1QX5m3zsXmCUdz8C38wiNB4cA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jfv/6BCJg8AS29X3Sp2UD+oOmhxuMxMQFSZi29y/O6b5kmMfIL8y9Kt+fOHcWTwLU1KaOgMdVraufasZgud0blMpIL6WiG6cp0Y4lQ0W54FJF7yhwNS9l3NYHQ/fgYXKFmQ56V1w5mnFJbp/EnkXTXwzy4AVGg2seJzZk6DgKaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vQ93vAmM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vQ93vAmM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A77DC4CEF7; Fri, 20 Mar 2026 19:26:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774034764; bh=yJiC1Pk7ovdXcihEau1QX5m3zsXmCUdz8C38wiNB4cA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=vQ93vAmMt6SS+0QmY3Q6b130RTuWW6iieav4WuMuniNMY3Zyw4AF9/s4UyRwnpXHB E3I5b5U6yb6hLgNO9+DrrdL2TlK+UXqjp+FLn3om2gNJ18BTQlm+8ArVBagvWVLqMX zzyF8DCrBP9pN4Wi9vlD1LV5zi/4ucDdbxKC/asvCK5Su/lM0TnMtFmpntUr4VlAb4 5johIFWc1g2Bodet6Ps4BAQwzb/qd6VJOBp3bXTdY5S85XDDuRemPbrY5OYvosckXQ p0HB1ovkew4HhOk/xNijMCUvXS28xepsyFz+0vkjd6ajDERzR7Jq+phxP5AMbnZNzO LxTSVyDL+AJgw== Message-ID: <229724b9-e128-4c8e-8d7a-36926afb76d2@kernel.org> Date: Fri, 20 Mar 2026 14:26:03 -0500 Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] rtc: cmos: Enable ACPI alarm if advertised in ACPI FADT To: "Rafael J. Wysocki" , linux-rtc@vger.kernel.org Cc: LKML , Linux ACPI , Alexandre Belloni References: <3964452.kQq0lBPeGt@rafael.j.wysocki> <9618535.CDJkKcVGEf@rafael.j.wysocki> Content-Language: en-US From: "Mario Limonciello (AMD) (kernel.org)" In-Reply-To: <9618535.CDJkKcVGEf@rafael.j.wysocki> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/14/2026 7:11 AM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > If the ACPI_FADT_FIXED_RTC flag is unset, the platform is declaring that > it supports the ACPI RTC fixed event which should be used instead of a > dedicated CMOS RTC IRQ. However, the driver only enables it when > is_hpet_enabled() returns true, which is questionable because there is > no clear connection between enabled HPET and signaling wakeup via the > ACPI RTC fixed event (for instance, the latter can be expected to work > on systems that don't include a functional HPET). > > Moreover, since use_hpet_alarm() returns false if use_acpi_alarm is set, > the ACPI RTC fixed event is effectively used instead of the HPET alarm > if the latter is functional, but there is no particular reason why it > could not be used otherwise. > > Accordingly, on x86 systems with ACPI, set use_acpi_alarm if > ACPI_FADT_FIXED_RTC is unset without looking at whether or not HPET is > enabled. > > Also, do the ACPI FADT check in use_acpi_alarm_quirks() before the DMI > BIOS year checks which are more expensive and it's better to skip them > if ACPI_FADT_FIXED_RTC is set. > > Signed-off-by: Rafael J. Wysocki This makes sense to me. Sorry for my delay, I kept on meaning to check a few machines and then more things came up and it fell lower. I did check 3 generations of AMD machines and I don't expect any problems from this change. Reviewed-by: Mario Limonciello (AMD) > --- > drivers/rtc/rtc-cmos.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > --- a/drivers/rtc/rtc-cmos.c > +++ b/drivers/rtc/rtc-cmos.c > @@ -817,6 +817,9 @@ static void rtc_wake_off(struct device * > #ifdef CONFIG_X86 > static void use_acpi_alarm_quirks(void) > { > + if (acpi_gbl_FADT.flags & ACPI_FADT_FIXED_RTC) > + return; > + > switch (boot_cpu_data.x86_vendor) { > case X86_VENDOR_INTEL: > if (dmi_get_bios_year() < 2015) > @@ -830,8 +833,6 @@ static void use_acpi_alarm_quirks(void) > default: > return; > } > - if (!is_hpet_enabled()) > - return; > > use_acpi_alarm = true; > } > > >