Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757277Ab3HAP4M (ORCPT ); Thu, 1 Aug 2013 11:56:12 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:57762 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756368Ab3HAP4K (ORCPT ); Thu, 1 Aug 2013 11:56:10 -0400 Date: Thu, 1 Aug 2013 11:56:09 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: boris brezillon cc: Greg Kroah-Hartman , Nicolas Ferre , Jean-Christophe Plagniol-Villard , Ludovic Desroches , , , Subject: Re: [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework In-Reply-To: <51FA7B6A.80106@overkiz.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 952 Lines: 27 On Thu, 1 Aug 2013, boris brezillon wrote: > > What happens if uclk isn't found but it is needed? > It will not fail but I guess the usb host won't work as the clock won't > be correctly > configured. > > I agree with you: this is not a good solution. > > Another option is to keep the previous version of this patch and put > uclk handling > in "#ifdef CONFIG_COMMON_CLK #endif" sections. > > Would this be acceptable ? Yes. However, a more elegant approach is to protect the relevant statements with: if (defined(CONFIG_COMMON_CLK)). This preprocessor evaluates this to a 0 or 1, so the compiler will not generate output for the protected source code if the symbol isn't defined. Alan Stern -- 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/