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Subject[PATCH v7 1/5] omap3isp: Modify clocks registration to avoid circular references
Date
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 <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
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 */
--
1.7.9.5


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