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 36EDA3BED4D; Tue, 17 Mar 2026 12:16:38 +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=1773749798; cv=none; b=jWM1Gygvuo2o95T2W2PBIzh5gwfCRct89eRomIMX8n8aPlb9AwO9BAlAjcNNfJetNe3Id/rBbKSfukUY5s/TIarllWGG3ZQi720qFl8G0TJNa8zuWWfOLzdlSfAjqjXuTDVmpG0cbTcM1Cf9FgjFqxo8YHvfJH4KxDl3ocT7NxY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773749798; c=relaxed/simple; bh=XuMBNNw7U9aZTQBP8fVUmWoBfgXagrRy+rF53mhLwhY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jgHAhSKbnRlzLK4hwTdO64oGrdB25CP72FYlv+OlhKLj1MDZUU6ZDWOi/h5Xtjh3VQfHcIBLzP/ZkP+C43up4uBBCo0ez0dqFoD+Udq91oeSlXcdeBWmO4bmInzaM04MGIFGD+FLBaOlcw4N2jyZtxMi+Q7I3vLxOIH3WnsVtYs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ksfCZJle; 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="ksfCZJle" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C6FBC4CEF7; Tue, 17 Mar 2026 12:16:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773749798; bh=XuMBNNw7U9aZTQBP8fVUmWoBfgXagrRy+rF53mhLwhY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ksfCZJleAYM43xEqGssBjYWWw0CjUNunMHVM2j52YnFS4q2iX8R1z1Rh5ELROKbcN NckCb6PaQrozN2QQeBokUG+Hifdxnd5EUcx5S8NHsHnjIGwUFzpMSMUymWEo+nq+fA RkU9miQyUNm9tesmhPx3aCmDrkitPBx1bbVIwmhDGVQTKtKe5oYolsZXvvKqvleCLO ikddGradpl1yYYi5lBuJkMmAdxoxU0sz7nAr7pILY2s/MJ5YfXwPpFDU0oRKEzzucJ weMesRV6nqTeX3qAI26rTXfzDgyw2SOR/Pu5SmimTL8ZyshueXwlC7qjb0Y85IsH1s wW0bdCLMhgZmg== Message-ID: <90efa4a3-7042-4fdd-9108-9234b0ba9573@kernel.org> Date: Tue, 17 Mar 2026 13:16:33 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] clk: add new Kconfig to control default behavior of disabling unused clocks To: Abel Vesa , Maxime Ripard Cc: Brian Masney , Jonathan Corbet , Shuah Khan , Michael Turquette , Stephen Boyd , Abel Vesa , Saravana Kannan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org References: <20260316-clk-ignore-unused-kconfig-v1-1-6e95a4fb0c94@redhat.com> <20260317-almond-leech-of-correction-2a2ef6@houat> From: Hans de Goede Content-Language: en-US, nl In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 17-Mar-26 13:14, Abel Vesa wrote: > On 26-03-17 08:30:24, Maxime Ripard wrote: >> Hi, >> >> On Mon, Mar 16, 2026 at 06:33:45PM -0400, Brian Masney wrote: >>> At the 2023 Linux Plumbers Conference in Richmond VA, there was a >>> discussion about how large number of systems need to boot with >>> clk_ignore_unused. Per the discussions at the conference, the existing >>> behavior in the clk core is broken, and there is a desire to completely >>> remove this functionality. >> >> Broken how? >> >> clk_ignore_unused is to a point where it's seriously cargo-culted and >> documented as a silver bullet, when in reality it's just a debug tool >> for broken drivers, and the driver must be fixed. >> >> But nobody is actually fixing it. >> >> See >> https://fedoraproject.org/wiki/Changes/Automatic_DTB_selection_for_aarch64_EFI_systems#How_To_Test >> for example. The affected clock could be marked as CLK_IS_CRITICAL, and >> fedora wouldn't have to package anything, change anything, etc. But no, >> the problem is clk_ignore_unused. > > Nope. Don't ever mark clocks as critical unless system crashes without > them. > > Here is an example or why clocks cannot be marked as critical but need > to be kept by the clk_ignore_unused: display driver probes later. > If you mark it as critical you just made the clock stay enabled even > when display is off. > > And this is just one example. Interesting, so maybe we need a new way flag to mark clocks as not to be turned off when turning unused clocks off, which does not block them getting disabled normally later ? (I was under the mistaken impression this is what CLK_IS_CRITICAL did) Regards, Hans