From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH 1/7] mmc: dw_mmc: lookup for optional biu and ciu clocks Date: Thu, 10 May 2012 14:43:42 +0100 Message-ID: <20120510134342.GA12727@n2100.arm.linux.org.uk> References: <1335935266-25289-1-git-send-email-thomas.abraham@linaro.org> <1335935266-25289-2-git-send-email-thomas.abraham@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-samsung-soc-owner@vger.kernel.org To: James Hogan Cc: Thomas Abraham , linux-samsung-soc@vger.kernel.org, patches@linaro.org, devicetree-discuss@lists.ozlabs.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, rob.herring@calxeda.com, grant.likely@secretlab.ca, kgene.kim@samsung.com, cjb@laptop.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Wed, May 02, 2012 at 03:53:53PM +0100, James Hogan wrote: > Hi >=20 > On 2 May 2012 06:07, Thomas Abraham wrote= : > > + =A0 =A0 =A0 if (IS_ERR(host->biu_clk)) > > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_info(&host->dev, "biu clock not a= vailable\n"); >=20 > In this case, should it set host->biu_clk to NULL or are clk_disable > and clk_put guaranteed to handle an IS_ERR value? I keep saying this. NULL must be treated as a valid reutrn value from clk_get() and must not use this as a sentinel. The clk namespace is that errors are indicated with IS_ERR(clk) returning true. Everything else must be assumed to be valid by drivers.