Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644AbbBKMTs (ORCPT ); Wed, 11 Feb 2015 07:19:48 -0500 Received: from mga14.intel.com ([192.55.52.115]:59172 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751785AbbBKMTq (ORCPT ); Wed, 11 Feb 2015 07:19:46 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,558,1418112000"; d="scan'208";a="453093223" Message-ID: <1423657177.31903.505.camel@linux.intel.com> Subject: Re: [PATCH] dmaengine: dw: support for clockless platforms From: Andy Shevchenko To: Russell King - ARM Linux Cc: Viresh Kumar , Heikki Krogerus , Vinod Koul , "linux-kernel@vger.kernel.org" , dmaengine@vger.kernel.org Date: Wed, 11 Feb 2015 14:19:37 +0200 In-Reply-To: <20150211120727.GQ8656@n2100.arm.linux.org.uk> References: <1421758677-183443-1-git-send-email-heikki.krogerus@linux.intel.com> <1423656159.31903.502.camel@linux.intel.com> <20150211120727.GQ8656@n2100.arm.linux.org.uk> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1745 Lines: 40 On Wed, 2015-02-11 at 12:07 +0000, Russell King - ARM Linux wrote: > On Wed, Feb 11, 2015 at 02:02:39PM +0200, Andy Shevchenko wrote: > > On Wed, 2015-02-11 at 10:10 +0800, Viresh Kumar wrote: > > > > chip->clk = devm_clk_get(chip->dev, "hclk"); > > > > - if (IS_ERR(chip->clk)) > > > > - return PTR_ERR(chip->clk); > > > > + if (IS_ERR(chip->clk)) { > > > > + if (PTR_ERR(chip->clk) == -ENOENT) > > > > + chip->clk = NULL; > > > > > > You don't need to set it to NULL, if CONFIG_HAVE_CLK isn't set > > > the dummy routines would take care of it. > > > > Yeah, but in our case we have CONFIG_HAVE_CLK=y and no clk is provided > > since IP is clockless. What could you suggest to do in such case? > > chip->clk = devm_clk_get(chip->dev, "hclk"); > if (IS_ERR(chip->clk) && PTR_ERR(chip->clk) != -ENOENT) > return PTR_ERR(chip->clk); > > You can then test for the presence of a clk via IS_ERR(chip->clk). > > I'm just debating whether we should add a clk_is_valid() inline function > to linux/clk.h to avoid these shouting tests, and make it easier for > people test this in a generic manner. I guess clock framework may handle whatever is gotten from clk_get(). In driver much cleaner to use direct calls with exceptions (like you can't get a valid clock rate from non-existing clock). So, what about just passing by the error code and doing nothing? -- Andy Shevchenko Intel Finland Oy -- 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/