From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 16 Oct 2015 14:31:39 -0700 From: Stephen Boyd To: York Sun Cc: linux-clk@vger.kernel.org, pmarrecas@outlook.com, Mike Turquette , Sebastian Hesselbarth , Guenter Roeck , Andrey Filippov , Paul Bolle Subject: Re: [Resend Patch v6] driver/clk/clk-si5338: Add common clock framework driver for si5338 Message-ID: <20151016213139.GE16437@codeaurora.org> References: <1444410574-28677-1-git-send-email-yorksun@freescale.com> <20151010000948.GW26883@codeaurora.org> <562165C3.1090103@freescale.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <562165C3.1090103@freescale.com> List-ID: On 10/16, York Sun wrote: > > > On 10/09/2015 05:09 PM, Stephen Boyd wrote: > > On 10/09, York Sun wrote: > >> +/* > >> + * To support multiple si5338 chips, we cannot use devm_clk_get because > >> + * each chip has its own clock sources. If device tree is not used, > >> + * platform driver should provide these clocks. Let the clocks be freed > >> + * automatically when device is unbound. We implement our own devm_of_clk_get. > >> + */ > >> +static void devm_of_clk_release(struct device *dev, void *res) > >> +{ > >> + clk_put(*(struct clk **)res); > >> +} > >> + > >> +static struct clk *devm_of_clk_get(struct device *dev, struct device_node *np, > > > > What is this? I don't get it at all. > > Maybe you can help me on this. > We have two ways to get parent clock. One is from device tree, the other is from > platform data. When the clock is from platform data, the consumer gets the clock > and passes it. The clock will be put by the consumer as well. When the parent > clock comes from device tree, what I am trying to do is to call of_clk_get(), > without worrying about to call clk_put() later when the driver is removed, so I > don't have to know where the parent clock data came from. > This driver should always use clk_get() then. If the mode is device tree, clk_get() will lookup the clock in DT and get it from there. If the mode is platform data, then we'll fallback to the clkdev method of clk_get(), which will look for a clk_lookup created for the device calling clk_get() + the connection id that was provided by the lookup creator. This driver should always call clk_put() on the clock when it's done with it, regardless of DT vs. platform data. > >> + /* > >> + * Important: Go through the procedure to check PLL locking > >> + * and other steps required by si5338 reference manual. > >> + */ > >> + ret = post_init(drvdata); > >> + if (ret) > >> + return ret; > >> + > >> + dev_dbg(&client->dev, "%s clocks are registered\n", id->name); > >> + > >> +#ifdef CONFIG_OF > > > > Remove this ifdef > > So we always use OF? No, the function is stubbed out if CONFIG_OF=n so there's no point to the ifdef. The compiler will optimize away the dead code. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project