Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932301AbaJWSFL (ORCPT ); Thu, 23 Oct 2014 14:05:11 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:39758 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932090AbaJWSFG (ORCPT ); Thu, 23 Oct 2014 14:05:06 -0400 Message-ID: <54494323.7030805@ti.com> Date: Thu, 23 Oct 2014 21:04:19 +0300 From: Grygorii Strashko User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Dmitry Torokhov CC: , "Rafael J. Wysocki" , , , Rob Herring , , , , , Geert Uytterhoeven , Ulf Hansson Subject: Re: [PATCH v3 1/5] PM / clock_ops: Add pm_clk_add_clk() References: <1414074182-25980-1-git-send-email-grygorii.strashko@ti.com> <1414074182-25980-2-git-send-email-grygorii.strashko@ti.com> <20141023154928.GC18714@dtor-ws> <54492A69.5070505@ti.com> <20141023171305.GA24671@dtor-ws> In-Reply-To: <20141023171305.GA24671@dtor-ws> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/23/2014 08:13 PM, Dmitry Torokhov wrote: > On Thu, Oct 23, 2014 at 07:18:49PM +0300, Grygorii Strashko wrote: >> On 10/23/2014 06:49 PM, Dmitry Torokhov wrote: >>> On Thu, Oct 23, 2014 at 05:22:58PM +0300, Grygorii Strashko wrote: >>>> From: Geert Uytterhoeven >>>> >>>> The existing pm_clk_add() allows to pass a clock by con_id. However, >>>> when referring to a specific clock from DT, no con_id is available. >>>> >>>> Add pm_clk_add_clk(), which allows to specify the struct clk * directly. >>>> >>>> CC: Ulf Hansson >>>> CC: Dmitry Torokhov >>>> Reviewed-by: Santosh Shilimkar >>>> Reviewed-by: Kevin Hilman >>>> Signed-off-by: Geert Uytterhoeven >>>> Signed-off-by: Grygorii Strashko >>>> --- >>>> drivers/base/power/clock_ops.c | 41 +++++++++++++++++++++++++++++++---------- >>>> include/linux/pm_clock.h | 8 ++++++++ >>>> 2 files changed, 39 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c >>>> index 7836930..f14b767 100644 >>>> --- a/drivers/base/power/clock_ops.c >>>> +++ b/drivers/base/power/clock_ops.c >>>> @@ -53,7 +53,8 @@ static inline int __pm_clk_enable(struct device *dev, struct clk *clk) >>>> */ >>>> static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce) >>>> { >>>> - ce->clk = clk_get(dev, ce->con_id); >>>> + if (!ce->clk) >>>> + ce->clk = clk_get(dev, ce->con_id); >>>> if (IS_ERR(ce->clk)) { >>>> ce->status = PCE_STATUS_ERROR; >>>> } else { >>>> @@ -63,15 +64,8 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce) >>>> } >>>> } >>>> >>>> -/** >>>> - * pm_clk_add - Start using a device clock for power management. >>>> - * @dev: Device whose clock is going to be used for power management. >>>> - * @con_id: Connection ID of the clock. >>>> - * >>>> - * Add the clock represented by @con_id to the list of clocks used for >>>> - * the power management of @dev. >>>> - */ >>>> -int pm_clk_add(struct device *dev, const char *con_id) >>>> +static int __pm_clk_add(struct device *dev, const char *con_id, >>>> + struct clk *clk) >>>> { >>>> struct pm_subsys_data *psd = dev_to_psd(dev); >>>> struct pm_clock_entry *ce; >>>> @@ -93,6 +87,8 @@ int pm_clk_add(struct device *dev, const char *con_id) >>>> kfree(ce); >>>> return -ENOMEM; >>>> } >>>> + } else { >>> >>> You need __clk_get(clk) here, otherwise when you will be removing clocks >>> you'll be dropping a reference that does not belong to you (as yiou have >>> not taken it). >> >> No, I don't ;) >> >> pm_clk_add_clk is intended to be used with valid pointer on clk, >> which means clk_get() has been called already. In our case: >> clk = of_clk_get(dev->of_node, i)); >> ret = pm_clk_add_clk(dev, clk); >> >> It's just a different way to fill list of clocks for device, >> once pm_clk_add_clk() is called - PM clock framework will be the owner >> of clock. > > No, this is not how the rest of refcounted APIs work in the kernel. You > do not take over other's references and if you need to store pointer to > refcounted object you are responsible for taking your own reference. See > how we work with device structures, OF nodes, etc, etc. > > The proper pattern here should be (unless the driver wants to hold on to > the clock for its own purposes): > > clk = of_clk_get(dev->of_node, i)); > ret = pm_clk_add_clk(dev, clk); > clk_put(clk); > > with pm_clk_add_clk() taking and managing _its own_ reference and the > caller (driver) managing _its_ reference. > > So FWIW strong NAK here from me. Ok. I'll update and resend. regards, -grygorii -- 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/