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 14810C6FD18 for ; Wed, 29 Mar 2023 14:13:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230321AbjC2ONE (ORCPT ); Wed, 29 Mar 2023 10:13:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230268AbjC2OMZ (ORCPT ); Wed, 29 Mar 2023 10:12:25 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F21B5FD9; Wed, 29 Mar 2023 07:11:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1680099103; x=1711635103; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=uqRixI+rCRUn5ojNLm8F/UrKpimmbseAK3K5c/AtPKI=; b=O2xupxpTWc403nesMbIbqSBhTiF/+boII9BxVuiejMdhab7M5ARk8RDS aOtRjoRkrtAHWnlXtOqjv+8TtQpddkTd7VmKrSCAgLph4iie0qgva0ytq LgXbGlkjpuox22As/bK0qGqVbX2wRM2KFjl+o6QrAnn6kmNzsRPINVi8k +gNi/gE7MbSz35WiDYSegBbN4QS+BWjZ3RDMVxeD+iUe1Ohz74vrZlIKe EYCMj6lb0QIiGda82CNHjtbhhFHI55qsttmJk36dneWIffAsJbHMUkNdD cFE3hP3UhJ9kSnZkmyjMmQB2JDsvHhtzuJS8xSEhkEo3XJPNctP3D5w9J g==; X-IronPort-AV: E=McAfee;i="6600,9927,10664"; a="342480942" X-IronPort-AV: E=Sophos;i="5.98,301,1673942400"; d="scan'208";a="342480942" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2023 07:06:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10664"; a="684280183" X-IronPort-AV: E=Sophos;i="5.98,301,1673942400"; d="scan'208";a="684280183" Received: from smile.fi.intel.com ([10.237.72.54]) by orsmga002.jf.intel.com with ESMTP; 29 Mar 2023 07:06:31 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1phWRZ-00A3Kf-03; Wed, 29 Mar 2023 17:06:29 +0300 Date: Wed, 29 Mar 2023 17:06:28 +0300 From: Andy Shevchenko To: Nuno =?iso-8859-1?Q?S=E1?= Cc: Mark Brown , "Sahin, Okan" , Lee Jones , Rob Herring , Krzysztof Kozlowski , Liam Girdwood , Jonathan Cameron , Lars-Peter Clausen , Cosmin Tanislav , Stephen Boyd , Caleb Connolly , Lad Prabhakar , "Bolboaca, Ramona" , ChiYuan Huang , "Tilki, Ibrahim" , William Breathitt Gray , Arnd Bergmann , ChiaEn Wu , Haibo Chen , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-iio@vger.kernel.org" Subject: Re: [PATCH v6 5/5] mfd: max77541: Add ADI MAX77541/MAX77540 PMIC Support Message-ID: References: <20230315175257.GJ9667@google.com> <60bbad1b38b8e3c9c3efefb0fb7b8d3cad7fa98c.camel@gmail.com> <9ba3c559e2fb685c941b02fcfddaeb82aefed6f7.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9ba3c559e2fb685c941b02fcfddaeb82aefed6f7.camel@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Wed, Mar 29, 2023 at 09:01:30AM +0200, Nuno Sá wrote: > On Tue, 2023-03-28 at 18:47 +0300, Andy Shevchenko wrote: > > On Tue, Mar 28, 2023 at 04:51:18PM +0200, Nuno Sá wrote: > > > On Tue, 2023-03-28 at 17:35 +0300, Andy Shevchenko wrote: > > > > On Tue, Mar 28, 2023 at 04:18:30PM +0200, Nuno Sá wrote: > > > > > On Tue, 2023-03-28 at 14:46 +0100, Mark Brown wrote: > > > > > > On Tue, Mar 28, 2023 at 03:26:44PM +0200, Nuno Sá wrote: > > > > > > > > > > > > > IIRC, regmap_read() is not really reentrant and it is used > > > > > > > in > > > > > > > the > > > > > > > IIO > > > > > > > driver on the sysfs interface. So, yeah, I think you need > > > > > > > the > > > > > > > regmap > > > > > > > lock and better just leave the config as is. Yes, the lock > > > > > > > is > > > > > > > opt- > > > > > > > out > > > > > > > so let's not disable it :) > > > > > > > > > > > > All the regmap operations are fully thread safe. > > > > > > > > > > Even if 'config->disable_locking' is set? I think that is > > > > > what's > > > > > being > > > > > discussed in here... > > > > > > > > In case the driver has its own lock to serialize IO how on earth > > > > the > > > > regmap > > > > lock is needed. That's what I asked the author of the driver. He > > > > told > > > > the code > > > > > > Well, if the driver has it's own locking, then sure we do not need > > > regmap's lock... > > > > > > > doesn't require the regmap lock, and I tend to believe the > > > > author. > > > > So, why to > > > > keep it? > > > > > > However, if you look at the adc driver, I can see plain > > > regmap_read() > > > calls without any "outside" locking. > > > > Then author of the code should know what they are doing. Right? > > In theory yes, but you know that's not always the case :) Exactly. That's why I want to hear from the author of the code to make sure they know _their_ code. -- With Best Regards, Andy Shevchenko