From nobody Sun Feb 8 00:50:08 2026 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 9D11838FF0B; Tue, 13 Jan 2026 13:36:57 +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=1768311417; cv=none; b=R8lMCdOcBHMu69A6f2ohCJxlkCFxGrLMYwXlRaKuyksQ86tD127D3GIVgcB7oXUo4ZtmhDH7hrj7XosqNrXxg1UOGoXeSfi8Go3h96IDWKcAO4e5LCR3FXxVsjniPgxn9sAoD/vA77KuSxgKN5A3+F1ZOx7quXguHlXfb7BpyLY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768311417; c=relaxed/simple; bh=IXvx5aXrBcUXshtJXld2okFqAwlbZa5hJRy3jy9dF+w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=nQmWoob8AmnFk05TThc3yXkP3wzN+occyiRhK6HL+TLDuEQMFtLExpDni7EvcdysZkaB54dKIbeOXZM2revn20bIcCTu36P4VdPiBmBpm/0VnKMooLUmHJ0mKAGjgXiqB1S6HVcEF3KEdlLjeMCNyfrnfYaFhxuWJhmXLdOo2w0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tcAZXn31; 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="tcAZXn31" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73CCCC16AAE; Tue, 13 Jan 2026 13:36:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768311417; bh=IXvx5aXrBcUXshtJXld2okFqAwlbZa5hJRy3jy9dF+w=; h=From:To:Cc:Subject:Date:From; b=tcAZXn31bkLBlcigInta1oir746tMWc6W1LBfKVnR3Y6CrzCBk72qV4vbD+6J62Ek uhn3E2kveTtrVeQFNB2Dmnhtp4RBdtFXv2uECqGilwEig4Zs7yY3vMS98KYQMx7h95 DY150KkW33ZyWW9zEei24+RBcW4rzB6fRh7wyFigROeDjYcBS+FQvw2oZlG1vPddvt 78Bf6owUYSQxgqJlA8wUtq8f10mgxqQgVaMcbTeG0CpnB/yHwRmu5jWGEb2LQFtTC9 9Nou0d6TpmnDdC8lHdElzX+qdfwB88InhfZoqtCW+zt4DUkybmDjqrYsHnGlORInpP K4qkExKffiJpA== From: "Rafael J. Wysocki" To: Linux ACPI Cc: LKML , Linux PM , Mario Limonciello , Srinivas Pandruvada Subject: [PATCH v1] ACPI: PM: s2idle: Add module parameter for LPS0 constraints checking Date: Tue, 13 Jan 2026 14:36:54 +0100 Message-ID: <2827214.mvXUDI8C0e@rafael.j.wysocki> Organization: Linux Kernel Development Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rafael J. Wysocki Commit 32ece31db4df ("ACPI: PM: s2idle: Only retrieve constraints when needed") attempted to avoid useless evaluation of LPS0 _DSM Function 1 in lps0_device_attach() because pm_debug_messages_on might never be set (and that is the case on production systems most of the time), but it turns out that LPS0 _DSM Function 1 is generally problematic on some platforms and causes suspend issues to occur when pm_debug_messages_on is set now. In Linux, LPS0 _DSM Function 1 is only useful for diagnostics and only in the cases when the system does not reach the deepest platform idle state during suspend-to-idle for some reason. If such diagnostics is not necessary, evaluating it is a loss of time, so using it along with the other pm_debug_messages_on diagnostics is questionable because the latter is expected to be suitable for collecting debug information even during production use of system suspend. For this reason, add a module parameter called check_lps0_constraints to control whether or not the list of LPS0 constraints will be checked in acpi_s2idle_prepare_late_lps0() and so whether or not to evaluate LPS0 _DSM Function 1 (once) in acpi_s2idle_begin_lps0(). Fixes: 32ece31db4df ("ACPI: PM: s2idle: Only retrieve constraints when need= ed") Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD) --- drivers/acpi/x86/s2idle.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/acpi/x86/s2idle.c +++ b/drivers/acpi/x86/s2idle.c @@ -28,6 +28,10 @@ static bool sleep_no_lps0 __read_mostly; module_param(sleep_no_lps0, bool, 0644); MODULE_PARM_DESC(sleep_no_lps0, "Do not use the special LPS0 device interf= ace"); =20 +static bool check_lps0_constraints __read_mostly; +module_param(check_lps0_constraints, bool, 0644); +MODULE_PARM_DESC(check_lps0_constraints, "Check LPS0 device constraints"); + static const struct acpi_device_id lps0_device_ids[] =3D { {"PNP0D80", }, {"", }, @@ -515,7 +519,7 @@ static struct acpi_scan_handler lps0_han =20 static int acpi_s2idle_begin_lps0(void) { - if (lps0_device_handle && !sleep_no_lps0 && pm_debug_messages_on && + if (lps0_device_handle && !sleep_no_lps0 && check_lps0_constraints && !lpi_constraints_table) { if (acpi_s2idle_vendor_amd()) lpi_device_get_constraints_amd(); @@ -540,7 +544,7 @@ static int acpi_s2idle_prepare_late_lps0 if (!lps0_device_handle || sleep_no_lps0) return 0; =20 - if (pm_debug_messages_on) + if (check_lps0_constraints) lpi_check_constraints(); =20 /* Screen off */