Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751685Ab3J2W2P (ORCPT ); Tue, 29 Oct 2013 18:28:15 -0400 Received: from perceval.ideasonboard.com ([95.142.166.194]:38653 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751086Ab3J2W2N (ORCPT ); Tue, 29 Oct 2013 18:28:13 -0400 From: Laurent Pinchart To: Sylwester Nawrocki Cc: linux-arm-kernel@lists.infradead.org, mturquette@linaro.org, linux@arm.linux.org.uk, jiada_wang@mentor.com, kyungmin.park@samsung.com, linux-kernel@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org, linux-mips@linux-mips.org, linux-sh@vger.kernel.org Subject: Re: [PATCH v7 1/5] omap3isp: Modify clocks registration to avoid circular references Date: Tue, 29 Oct 2013 23:28:37 +0100 Message-ID: <16467881.81yEf9zq68@avalon> User-Agent: KMail/4.10.5 (Linux/3.10.7-gentoo-r1; KDE/4.10.5; x86_64; ; ) In-Reply-To: <1383076268-8984-2-git-send-email-s.nawrocki@samsung.com> References: <1383076268-8984-1-git-send-email-s.nawrocki@samsung.com> <1383076268-8984-2-git-send-email-s.nawrocki@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3774 Lines: 109 Hi Sylwester, Thank you for the patch. On Tuesday 29 October 2013 20:51:04 Sylwester Nawrocki wrote: > The clock core code is going to be modified so clk_get() takes > reference on the clock provider module. Until the potential circular > reference issue is properly addressed, we pass NULL as as the first > argument to clk_register(), in order to disallow sub-devices taking > a reference on the ISP module back trough clk_get(). This should > prevent locking the modules in memory. > > Cc: Laurent Pinchart > Signed-off-by: Sylwester Nawrocki > Signed-off-by: Kyungmin Park Acked-by: Laurent Pinchart Do you plan to push this to mainline as part of this patch series ? I don't have pending patches for the omap3isp that would conflict with this patch, so that would be fine with me. > --- > This patch has been "compile tested" only. > > --- > drivers/media/platform/omap3isp/isp.c | 22 ++++++++++++++++------ > drivers/media/platform/omap3isp/isp.h | 1 + > 2 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/drivers/media/platform/omap3isp/isp.c > b/drivers/media/platform/omap3isp/isp.c index df3a0ec..286027a 100644 > --- a/drivers/media/platform/omap3isp/isp.c > +++ b/drivers/media/platform/omap3isp/isp.c > @@ -290,9 +290,11 @@ static int isp_xclk_init(struct isp_device *isp) > struct clk_init_data init; > unsigned int i; > > + for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) > + isp->xclks[i].clk = ERR_PTR(-EINVAL); > + > for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) { > struct isp_xclk *xclk = &isp->xclks[i]; > - struct clk *clk; > > xclk->isp = isp; > xclk->id = i == 0 ? ISP_XCLK_A : ISP_XCLK_B; > @@ -305,10 +307,15 @@ static int isp_xclk_init(struct isp_device *isp) > init.num_parents = 1; > > xclk->hw.init = &init; > - > - clk = devm_clk_register(isp->dev, &xclk->hw); > - if (IS_ERR(clk)) > - return PTR_ERR(clk); > + /* > + * The first argument is NULL in order to avoid circular > + * reference, as this driver takes reference on the > + * sensor subdevice modules and the sensors would take > + * reference on this module through clk_get(). > + */ > + xclk->clk = clk_register(NULL, &xclk->hw); > + if (IS_ERR(xclk->clk)) > + return PTR_ERR(xclk->clk); > > if (pdata->xclks[i].con_id == NULL && > pdata->xclks[i].dev_id == NULL) > @@ -320,7 +327,7 @@ static int isp_xclk_init(struct isp_device *isp) > > xclk->lookup->con_id = pdata->xclks[i].con_id; > xclk->lookup->dev_id = pdata->xclks[i].dev_id; > - xclk->lookup->clk = clk; > + xclk->lookup->clk = xclk->clk; > > clkdev_add(xclk->lookup); > } > @@ -335,6 +342,9 @@ static void isp_xclk_cleanup(struct isp_device *isp) > for (i = 0; i < ARRAY_SIZE(isp->xclks); ++i) { > struct isp_xclk *xclk = &isp->xclks[i]; > > + if (!IS_ERR(xclk->clk)) > + clk_unregister(xclk->clk); > + > if (xclk->lookup) > clkdev_drop(xclk->lookup); > } > diff --git a/drivers/media/platform/omap3isp/isp.h > b/drivers/media/platform/omap3isp/isp.h index cd3eff4..1498f2b 100644 > --- a/drivers/media/platform/omap3isp/isp.h > +++ b/drivers/media/platform/omap3isp/isp.h > @@ -135,6 +135,7 @@ struct isp_xclk { > struct isp_device *isp; > struct clk_hw hw; > struct clk_lookup *lookup; > + struct clk *clk; > enum isp_xclk_id id; > > spinlock_t lock; /* Protects enabled and divider */ -- Regards, Laurent Pinchart -- 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/