Hi, Laurent
On 12/2/2014 6:26 AM, Laurent Pinchart wrote:
Hi Josh,
(CC'ing the devicetree@xxxxxxxxxxxxxxx mailing list)
Thank you for the patch.
On Friday 28 November 2014 18:28:26 Josh Wu wrote:
The master clock can be optional. It's a common clock framework clock.
It can make sensor output a pixel clock to the camera interface.
If you just use a external oscillator clock as the master clock, then,
just don't need set 'mck' in dt node.
Signed-off-by: Josh Wu <josh.wu@xxxxxxxxx>
---
drivers/media/i2c/soc_camera/ov2640.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/media/i2c/soc_camera/ov2640.c
b/drivers/media/i2c/soc_camera/ov2640.c index 6506126..06c2aa9 100644
--- a/drivers/media/i2c/soc_camera/ov2640.c
+++ b/drivers/media/i2c/soc_camera/ov2640.c
@@ -13,6 +13,7 @@
* published by the Free Software Foundation.
*/
+#include <linux/clk.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/i2c.h>
@@ -31,6 +32,8 @@
#define VAL_SET(x, mask, rshift, lshift) \
((((x) >> rshift) & mask) << lshift)
+#define DEFAULT_MASTER_CLK_FREQ 25000000
+
/*
* DSP registers
* register offset for BANK_SEL == BANK_SEL_DSP
@@ -284,6 +287,7 @@ struct ov2640_priv {
struct v4l2_ctrl_handler hdl;
u32 cfmt_code;
struct v4l2_clk *clk;
+ struct clk *master_clk;
const struct ov2640_win_size *win;
struct soc_camera_subdev_desc ssdd_dt;
@@ -746,6 +750,7 @@ static int ov2640_s_power(struct v4l2_subdev *sd, int
on) struct soc_camera_subdev_desc *ssdd = soc_camera_i2c_to_desc(client);
struct ov2640_priv *priv = to_ov2640(client);
struct v4l2_clk *clk;
+ int ret = 0;
if (!priv->clk) {
clk = v4l2_clk_get(&client->dev, "mclk");
@@ -755,6 +760,16 @@ static int ov2640_s_power(struct v4l2_subdev *sd, int
on) priv->clk = clk;
}
+ if (!IS_ERR(priv->master_clk)) {
The clock should be mandatory, you can thus drop this check.
OK. sure.
+ if (on)
+ ret = clk_prepare_enable(priv->master_clk);
+ else
+ clk_disable_unprepare(priv->master_clk);
+
+ if (ret)
+ return ret;
You can move the error check inside the first branch of the if and remove the
ret = 0 initialization above.
+ }
+
return soc_camera_set_power(&client->dev, ssdd, priv->clk, on);
If this call fails you should disable or enable the clock to undo the
enable/disable above.
ah, I totally forget this. will fix in next version. Thanks.
}
@@ -1153,6 +1168,16 @@ static int ov2640_probe(struct i2c_client *client,
}
}
+ priv->master_clk = devm_clk_get(&client->dev, "mck");
+ if (!IS_ERR(priv->master_clk)) {
+ /* Set ISI_MCK's frequency, it should be faster than pixel
+ * clock.
+ */
+ ret = clk_set_rate(priv->master_clk, DEFAULT_MASTER_CLK_FREQ);
The clock frequency should be system-dependent. For the DT case an easy
implementation would be to use the assigned-clock-rates to set the desired
clock frequency is case of a variable clock, as adding a sensor-specific
property to specify the desired clock frequency only to read that property in
the driver and call clk_set_rate() seems a bit pointless to me.
I tried assigned-clock-rates and it works fine.
The only issue is the it cannot used by multiple nodes. But I think I
can put a comments in the dt node for this.
Thanks.
Best Regards,
Josh Wu
+ if (ret < 0)
+ return ret;
+ }
+
v4l2_i2c_subdev_init(&priv->subdev, client, &ov2640_subdev_ops);
v4l2_ctrl_handler_init(&priv->hdl, 2);
v4l2_ctrl_new_std(&priv->hdl, &ov2640_ctrl_ops,
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