From mboxrd@z Thu Jan 1 00:00:00 1970 From: sergei.shtylyov@cogentembedded.com (Sergei Shtylyov) Date: Thu, 01 Aug 2013 21:30:08 +0400 Subject: [PATCH] USB: ohci-at91: add usb_clk for transition to common clk framework In-Reply-To: References: Message-ID: <51FA9B20.3080304@cogentembedded.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hello. On 08/01/2013 07:56 PM, Alan Stern 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 You probably meant IS_ENABLED() or IS_BUIILTIN()? Or is there something I don't know about gcc 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 WBR, Sergei