From mboxrd@z Thu Jan 1 00:00:00 1970 From: sylvester.nawrocki@gmail.com (Sylwester Nawrocki) Date: Wed, 30 Oct 2013 00:57:52 +0100 Subject: [PATCH v7 1/5] omap3isp: Modify clocks registration to avoid circular references In-Reply-To: <16467881.81yEf9zq68@avalon> References: <1383076268-8984-1-git-send-email-s.nawrocki@samsung.com> <1383076268-8984-2-git-send-email-s.nawrocki@samsung.com> <16467881.81yEf9zq68@avalon> Message-ID: <52704B80.2040507@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Laurent, (adding Mauro and LMML at Cc) On 10/29/2013 11:28 PM, Laurent Pinchart wrote: > 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. Thanks, yes I thought this patch might be merged together through the clk tree, if Mike is willing to take it and we get yours and Mauro's Ack on it. >> --- >> 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, Sylwester