From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sylwester Nawrocki Subject: Re: ABBA deadlock in Common Clock Framework Date: Wed, 02 Jul 2014 14:41:54 +0200 Message-ID: <53B3FE12.3000608@samsung.com> References: <53B3E5F8.80501@samsung.com> <20140702114924.GC3679@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:45513 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297AbaGBMl7 (ORCPT ); Wed, 2 Jul 2014 08:41:59 -0400 In-reply-to: <20140702114924.GC3679@tbergstrom-lnx.Nvidia.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Peter De Schrijver , Tomasz Figa Cc: "linux-kernel@vger.kernel.org" , =?UTF-8?B?VG9tYXN6IFN0YW5pc8WCYXdza2k=?= , "linux-samsung-soc@vger.kernel.org" , Mike Turquette , Wolfram Sang , Andrzej Hajda , Mark Brown , Lee Jones , "linux-arm-kernel@lists.infradead.org" On 02/07/14 13:49, Peter De Schrijver wrote: > Or if you use notifiers which use i2c... See also > http://comments.gmane.org/gmane.linux.kernel/1553699. One workaround is to > always leave the clock of the i2c controller in a prepared state. Keeping the clock always prepared might not be that bad, given prepare/unprepare ops are empty on Exynos and I'd say chances this ever changes are very low. Now we have just an overhead of calling to the clock core before and after each single I2C transfer. -- Regards, Sylwester From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.nawrocki@samsung.com (Sylwester Nawrocki) Date: Wed, 02 Jul 2014 14:41:54 +0200 Subject: ABBA deadlock in Common Clock Framework In-Reply-To: <20140702114924.GC3679@tbergstrom-lnx.Nvidia.com> References: <53B3E5F8.80501@samsung.com> <20140702114924.GC3679@tbergstrom-lnx.Nvidia.com> Message-ID: <53B3FE12.3000608@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/07/14 13:49, Peter De Schrijver wrote: > Or if you use notifiers which use i2c... See also > http://comments.gmane.org/gmane.linux.kernel/1553699. One workaround is to > always leave the clock of the i2c controller in a prepared state. Keeping the clock always prepared might not be that bad, given prepare/unprepare ops are empty on Exynos and I'd say chances this ever changes are very low. Now we have just an overhead of calling to the clock core before and after each single I2C transfer. -- Regards, Sylwester