From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f174.google.com (mail-pg1-f174.google.com [209.85.215.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 012B3235045 for ; Tue, 25 Nov 2025 16:20:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764087638; cv=none; b=P7y0i6WzF2Bahlu7CarDeCctfh93iaeRhbV3T8PuD+rkzg2dBDJDgiazI1YU+uMokqtXo+daB51KhZK3mEUyb+EgA+dIxPNQtz7Zid+h2NLX05FcWuebTFkcWaK5GmqXqoPdSs85DtGr9l1ky+y3zShC+2V3wlaQS2IN979GP9U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764087638; c=relaxed/simple; bh=eJ/IMjGulEI8QmjGtE/6iZTat616jmFMM5GjWfzZprc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gSfT7EdpaobOJ5fiPSWOhwWJqs9bipHa19KioVcCp5KX7+7S9dkS/BXBVYf12wcz2KeTDUGKfli0yzcSJoLnJVH9m/FAIc8OXQJKcYNhEAPtvI/XGuGqWmijJ9T/dR7IUMF7vJvhaV27flZD1GEmRxlI0Vy2hkE2JUwlzb3fMwI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=m8pqydK0; arc=none smtp.client-ip=209.85.215.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="m8pqydK0" Received: by mail-pg1-f174.google.com with SMTP id 41be03b00d2f7-bc09b3d3afeso3111503a12.0 for ; Tue, 25 Nov 2025 08:20:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1764087636; x=1764692436; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=qZ1eFsM5Tf65QYOWpuLGzqCys5d89vyL8hwXtzNFx0s=; b=m8pqydK0/1LM6RTMUJvo+Lm3LHPrxyJXdiNi3oFhWUuWyOlgAAnHbngCi1KaFd9Qcv QyzDY9yCXkm6dRagxrM8eAkx5/kaVPhSIpYdAkO9Uw/Pi3uo7I7Me1h/HGkXaTGGp2z6 byf69FIKY5rw7CVMKl5Kze6fR4g5A+tcMHXIE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764087636; x=1764692436; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=qZ1eFsM5Tf65QYOWpuLGzqCys5d89vyL8hwXtzNFx0s=; b=fVkeIZ6wK2nuWkK+LQPFx7HdWVRj+H3pXxa/CB/nfMdDiBdeK0BOUTiFew3fWWqs7P N0aJ52oR5ZyZj9N/uLGwMUhPlFUzbpDeghk6WNEq0WCJ36QUsC8cdEgiFmDp5XVbQUM0 goYuN8jMiTPBiswuvElOW+vL8Pa09MLXtPyqwQXSm2EvXmvRdWe6q+qKdanN7yUqtfEk wAH2J3WISSF5gz4C3I7CrKoF3lPx0RhCT1esDJFi/v6R9T4iS8anFgiUeQGfdSjis8GH gN/XpDlc2qQOZKRzrkv/vHBjEu5cmDlaO2Uy4tHkWwt/zlU8jHFiZJXXrx21RaYfw/AL YzLQ== X-Forwarded-Encrypted: i=1; AJvYcCWCaQ/mnJTTWnhObFyUvoXsfgxEKkjdubSY7BFeL9jY/JPR/bdaOzbapMg0EX1cz3FpnC4HeyQ=@vger.kernel.org X-Gm-Message-State: AOJu0YygR2WK4GEOqTaU7vANLHMDqL13RX6b1bX42e9P+XTRIUoKPAwJ w+324CtdE4OWLSeciP2QFXoz+ZU89Qn28TboYnfLjo/D9fkwsqf4Qh0pWnqJ9Xkp+w== X-Gm-Gg: ASbGncsH91SR8ugjiRke5h6eZMlU7Yscvck5TX/4xTlYaGU5/1rmn6fH/1gy55czNzR kQEM6PB9JE544t9i8Uuv1CTzV4n77Tz4ae5MZ/lE5Aat+4CprrctnrJwb9QXJCdZHXHGoQTXPnZ /SnKDIMJItNP7W/G1NrPRzMrpFqrlCZDHS8BzsyxijTM7zGaTC4kNrGIQLAcIgJPLzBP9tvRsZ5 rTCkKNY7yDezLt6sNs4KZQC8KaocGOn97TZNLBLys8dx814wYusAXcSzBLsF+vHHYb8KunThjEx /SwmUi6WToBv1lX572WvZpMkwPY7J5qQ3TQ1RvvnLaFkdql4eKG6CTJGxG3fQ64ajLB7kiwa0Mo VVlvWLQJ7r5U/vQgFM2Zxrf9T6GCa5ldM5OAfCSQzRPVbLlFzBJX6p5025ozE3GjFZ1JlbhBQs/ UaZCpvlysVO1GShVcIEWgDsvGA/Zlc80VaxMF+LNXS0A2ARRDkXA== X-Google-Smtp-Source: AGHT+IHbxub078qD6r8lEEf/qWg01tDyiVQO7hyfzM7kwN7R7kHugcJNQAoH42YI5h55+GaIaK5kUQ== X-Received: by 2002:a05:693c:600f:b0:2a4:7352:dab1 with SMTP id 5a478bee46e88-2a71a127485mr10175866eec.36.1764087635917; Tue, 25 Nov 2025 08:20:35 -0800 (PST) Received: from localhost ([2a00:79e0:2e7c:8:62e0:9ddd:dee9:122b]) by smtp.gmail.com with UTF8SMTPSA id 5a478bee46e88-2a93c5562b2sm13362986eec.3.2025.11.25.08.20.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 Nov 2025 08:20:35 -0800 (PST) Date: Tue, 25 Nov 2025 08:20:34 -0800 From: Brian Norris To: Bjorn Helgaas Cc: Mika Westerberg , "Rafael J . Wysocki" , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] PCI/PM: Avoid redundant delays on D3hot->D3cold Message-ID: References: <20251003154008.1.I7a21c240b30062c66471329567a96dceb6274358@changeid> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251003154008.1.I7a21c240b30062c66471329567a96dceb6274358@changeid> On Fri, Oct 03, 2025 at 03:40:09PM -0700, Brian Norris wrote: > From: Brian Norris > > When transitioning to D3cold, __pci_set_power_state() will first > transition a device to D3hot. If the device was already in D3hot, this > will add excess work: > (a) read/modify/write PMCSR; and > (b) excess delay (pci_dev_d3_sleep()). > > For (b), we already performed the necessary delay on the previous D3hot > entry; this was extra noticeable when evaluating runtime PM transition > latency. > > Check whether we're already in the target state before continuing. > > Note that __pci_set_power_state() already does this same check for other > state transitions, but D3cold is special because __pci_set_power_state() > converts it to D3hot for the purposes of PMCSR. > > This seems to be an oversight in commit 0aacdc957401 ("PCI/PM: Clean up > pci_set_low_power_state()"). > > Fixes: 0aacdc957401 ("PCI/PM: Clean up pci_set_low_power_state()") > Cc: > Signed-off-by: Brian Norris > Signed-off-by: Brian Norris I'd like to know the status of this patch, with the merge window approaching. It sounds like people agreed it fixes a confirmed regression. I also don't think the request to remove all power state management from all drivers was a reasonable one. Brian