From mboxrd@z Thu Jan 1 00:00:00 1970 From: josh.wu@atmel.com (Josh Wu) Date: Wed, 3 Dec 2014 17:54:49 +0800 Subject: [PATCH 3/4] media: ov2640: add a master clock for sensor In-Reply-To: <2284801.0jEi8Kph7L@avalon> References: <1417170507-11172-1-git-send-email-josh.wu@atmel.com> <1417170507-11172-4-git-send-email-josh.wu@atmel.com> <2284801.0jEi8Kph7L@avalon> Message-ID: <547EDDE9.7070107@atmel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, Laurent On 12/2/2014 6:26 AM, Laurent Pinchart wrote: > Hi Josh, > > (CC'ing the devicetree at vger.kernel.org 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 >> --- >> 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 >> #include >> #include >> #include >> @@ -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,