From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CB27C77B73 for ; Tue, 2 May 2023 06:50:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233617AbjEBGub (ORCPT ); Tue, 2 May 2023 02:50:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233507AbjEBGuT (ORCPT ); Tue, 2 May 2023 02:50:19 -0400 Received: from mx1.tq-group.com (mx1.tq-group.com [93.104.207.81]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A8E7D4237; Mon, 1 May 2023 23:50:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tq-group.com; i=@tq-group.com; q=dns/txt; s=key1; t=1683010209; x=1714546209; h=from:to:subject:date:message-id:in-reply-to:references: mime-version:content-transfer-encoding; bh=YkZqd9ppIY7yEIAiINZ3ndGmS/bfhayyJibhgAwO8Ds=; b=Vrod4UF0J7aSDZ83RWJ5VxHmEWki6MczMcAplYsmpEfQ1lXc3+eeFfWM tYMQrNWj36DGUQKqiy857CgCIxD5CjIGsxZbQljXtgBmT1M0AZad5TUGC m+/9MA1t6p5WqaSht0DOttgnyVJ9+0qidVfoYByuKGEN2uUH4vPgfAXuM UxPMs5qRJ1iKbxdj/ILTSeZ7OmTR1GeCElyqQwmPP5RSfB5oHggOxJKEg T4ousCzXUhIvOZhHimYrlJLM681gCgYEZvTXLLBt2tOhI1Rd2gKf9LSeP uzK4+f1vKevbv0DDJRLwLhR/ddlVD5bu251zIjnj3HAITS01prVqam3LH g==; X-IronPort-AV: E=Sophos;i="5.99,243,1677538800"; d="scan'208";a="30655272" Received: from unknown (HELO tq-pgp-pr1.tq-net.de) ([192.168.6.15]) by mx1-pgp.tq-group.com with ESMTP; 02 May 2023 08:50:06 +0200 Received: from mx1.tq-group.com ([192.168.6.7]) by tq-pgp-pr1.tq-net.de (PGP Universal service); Tue, 02 May 2023 08:50:06 +0200 X-PGP-Universal: processed; by tq-pgp-pr1.tq-net.de on Tue, 02 May 2023 08:50:06 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tq-group.com; i=@tq-group.com; q=dns/txt; s=key1; t=1683010206; x=1714546206; h=from:to:subject:date:message-id:in-reply-to:references: mime-version:content-transfer-encoding; bh=YkZqd9ppIY7yEIAiINZ3ndGmS/bfhayyJibhgAwO8Ds=; b=dPrYNrEwCA6bui24GyFYdJ6BXqoQavuC/GRQo02bZvpTFrwe4O4LykyE m/CWzysdUm/95BL8+v+nkBd4xkRiLrQOZCfHmkgCZKSGMVc7Wl4yKMmST kEoEN2FXoPmhViE8ozvQgMUwpHSIED/9tAUV12Xo4R4WEIY0DzQIpbdNU 9+jI/2RfXD76RZ8Gk9RkSa6MnuauZQbsw/0ksJaYvn7e0z0Roivwy2spt 2JolWpXZ4hIdGBNlIPof5zPaD2+WB5RXW7hl9m/8N1PQ8fSE/3o+iMC8k mfWumxNqCruVPlSdRa23JOHJ+E5ZVKp5a3wo+SxaZhoI5ZSy9GMFc/+6U Q==; X-IronPort-AV: E=Sophos;i="5.99,243,1677538800"; d="scan'208";a="30655271" Received: from vtuxmail01.tq-net.de ([10.115.0.20]) by mx1.tq-group.com with ESMTP; 02 May 2023 08:50:06 +0200 Received: from steina-w.localnet (unknown [10.123.53.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by vtuxmail01.tq-net.de (Postfix) with ESMTPSA id 80EF4280056; Tue, 2 May 2023 08:50:06 +0200 (CEST) From: Alexander Stein To: Wolfram Sang , Alexander Stein , Marc Kleine-Budde , NXP Linux Team , "A. Sverdlin" , Dong Aisheng , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] i2c: lpi2c: cache peripheral clock rate Date: Tue, 02 May 2023 08:50:06 +0200 Message-ID: <2143344.irdbgypaU6@steina-w> Organization: TQ-Systems GmbH In-Reply-To: References: <20230310130815.562418-1-alexander.sverdlin@siemens.com> <4797405.GXAFRqVoOG@steina-w> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Wolfgang, Am Sonntag, 30. April 2023, 09:05:55 CEST schrieb Wolfram Sang: > * PGP Signed by an unknown key >=20 > > > IIRC this is a general problem^w limitation of the clock framework, > > > clock providers cannot use clocks themselves in certain callback, e.g. > > > set_rate. > >=20 > > Well, that's essentially impossible when this clock provider is attached > > via i2c. i2c transfers potentially need to change or prepare clocks. >=20 > So, as I get it, this is not a specific lpi2c problem but affecting any > I2C controller driver which uses get_rate() to setup a transfer to a > remote I2C clock provider? And this lockdep warning is a false-positive? Yes, IMHO this could potentially occur on every I2C controller driver, if a= =20 clock provider while holding the clk_prepare_lock, e.g. during registration= ,=20 issues an i2c transfer. I'm not so sure if this is a false-positive, but more like trying to do a=20 nested lock. Best regards Alexander =2D-=20 TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/