From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH 2/2] i2c: designware: Add support for a bus clock Date: Tue, 17 Jul 2018 17:47:19 +0300 Message-ID: References: <1531731553-22979-1-git-send-email-phil.edworthy@renesas.com> <1531731553-22979-3-git-send-email-phil.edworthy@renesas.com> <20180717120737.bipotpki3yhn6klf@verge.net.au> <40f2729f38bd565a829d60d9cc8f508e33b0dc65.camel@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Phil Edworthy , Simon Horman Cc: Jarkko Nikula , Geert Uytterhoeven , "linux-i2c@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-renesas-soc@vger.kernel.org" , Mika Westerberg List-Id: linux-i2c@vger.kernel.org On Tue, 2018-07-17 at 14:40 +0000, Phil Edworthy wrote: > Hi Andy, > > On 17 July 2018 15:19, Andy Shevchenko wrote: > > On Tue, 2018-07-17 at 12:42 +0000, Phil Edworthy wrote: > > > > > > While your point sounds valid (don't remember how clk_get() is > > > > implemented), NULL is also OK to have. > > > > > > Ok as in there is no bus clock, right? > > > So it should be: > > > if (!IS_ERR_OR_NULL (dev->busclk)) > > > > Nope, NULL is no error case for optional clock. > > I must be missing something here... See how clk_prepare_enable() is implemented. > I agree that NULL for an optional clock is not an error. However, the > code above is now: > + if (prepare) { > + /* Optional bus clock */ > + if (!IS_ERR_OR_NULL(dev->busclk)) { Check for NULL is redundant. > + ret = clk_prepare_enable(dev->busclk); > + if (ret) > + return ret; > + } > + > return clk_prepare_enable(dev->clk); > + } > > So, if you have a valid busclk, it gets enabled, otherwise it is > left alone. -- Andy Shevchenko Intel Finland Oy