Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161021Ab2JXRck (ORCPT ); Wed, 24 Oct 2012 13:32:40 -0400 Received: from mail-vc0-f174.google.com ([209.85.220.174]:37421 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935257Ab2JXRci (ORCPT ); Wed, 24 Oct 2012 13:32:38 -0400 MIME-Version: 1.0 In-Reply-To: <1351089926-32161-3-git-send-email-lee.jones@linaro.org> References: <1351089926-32161-1-git-send-email-lee.jones@linaro.org> <1351089926-32161-3-git-send-email-lee.jones@linaro.org> Date: Wed, 24 Oct 2012 19:32:37 +0200 Message-ID: Subject: Re: [PATCH 2/6] pinctrl: Update clock handling for the pinctrl-nomadik GPIO driver From: Linus Walleij To: Lee Jones , Ulf Hansson Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, arnd@arndb.de, linus.walleij@stericsson.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1637 Lines: 47 On Wed, Oct 24, 2012 at 4:45 PM, Lee Jones wrote: > The clock framework has changed somewhat and it's now better to > invoke clock_prepare_enable() and clk_disable_unprepare() rather > than the legacy clk_enable() and clk_disable() calls. This patch > converts the Nomadik Pin Control driver to the new framework. > > Signed-off-by: Lee Jones (...) > - clk_enable(chip->clk); > + clk_prepare_enable(chip->clk); (...) > - clk_disable(chip->clk); > + clk_disable_unprepare(chip->clk); (Repeated for each occurence.) Is this *really* causing a regression? I mean the driver begin like this in nmk_gpio_probe(): clk = devm_clk_get(&dev->dev, NULL); if (IS_ERR(clk)) { ret = PTR_ERR(clk); goto out; } clk_prepare(clk); Then it leaves the clock prepared. So the clock is always prepared. You would only need to enable/disable it at times. And the semantics of the clk_enable/clk_disable call pair is such that it is fastpath and should be real quick, and that is exactly why we're using it repeatedly like that. Inserting clk_unprepare() effectively could make the whole driver a lot slower, so convince me on this one. ... I suspect the real bug (if there is one) must be in the clock implementation. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/