media: ov6650: Simplify clock divisor calculation

As appears from an analysis of to_clkrc() helper code after its
pclk_limit argument has been dropped, its result no longer depends on
another argument - pclk_max.  Moreover, assuming that a constant value
of FRAME_RATE_MAX is always used as a denominator of the only
significant argument left - a struct v4l2_fract, the result in fact
depends only on the numerator value of that argument.  As a further
consequence, it no longer makes sense to recalculate frame intervals by
converting them forth and back with a GET_CLKRC_DIV(to_clkrc(tpf))
construct.

Drop use of GET_CLKRC_DIV() on results of to_clkrc() where possible -
use the frame interval value directly.  Furthermore, replace the
to_clkrc() helper function with a simple macro and update its users to
always use FRAME_RATE_MAX as frame interval denominator and pass only
its numerator as an argument.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/i2c/ov6650.c b/drivers/media/i2c/ov6650.c
index a502444..61ddd4e 100644 (file)
--- a/drivers/media/i2c/ov6650.c
+++ b/drivers/media/i2c/ov6650.c
@@ -545,18 +545,7 @@ static bool is_unscaled_ok(int width, int height, struct v4l2_rect *rect)
        return width > rect->width >> 1 || height > rect->height >> 1;
 }
 
-static u8 to_clkrc(struct v4l2_fract *timeperframe, unsigned long pclk_max)
-{
-       unsigned long pclk;
-
-       if (timeperframe->numerator && timeperframe->denominator)
-               pclk = pclk_max * timeperframe->denominator /
-                               (FRAME_RATE_MAX * timeperframe->numerator);
-       else
-               pclk = pclk_max;
-
-       return (pclk_max - 1) / pclk;
-}
+#define to_clkrc(div)  ((div) - 1)
 
 /* set the format we will capture in */
 static int ov6650_s_fmt(struct v4l2_subdev *sd, struct v4l2_mbus_framefmt *mf)
@@ -650,7 +639,7 @@ static int ov6650_s_fmt(struct v4l2_subdev *sd, struct v4l2_mbus_framefmt *mf)
        mclk = 12000000;
        dev_dbg(&client->dev, "using 12MHz input clock\n");
 
-       clkrc |= to_clkrc(&priv->tpf, priv->pclk_max);
+       clkrc |= to_clkrc(priv->tpf.numerator);
 
        pclk = priv->pclk_max / GET_CLKRC_DIV(clkrc);
        dev_dbg(&client->dev, "pixel clock divider: %ld.%ld\n",
@@ -749,9 +738,7 @@ static int ov6650_g_frame_interval(struct v4l2_subdev *sd,
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        struct ov6650 *priv = to_ov6650(client);
 
-       ival->interval.numerator = GET_CLKRC_DIV(to_clkrc(&priv->tpf,
-                                                         priv->pclk_max));
-       ival->interval.denominator = FRAME_RATE_MAX;
+       ival->interval = priv->tpf;
 
        dev_dbg(&client->dev, "Frame interval: %u/%u s\n",
                ival->interval.numerator, ival->interval.denominator);
@@ -766,7 +753,6 @@ static int ov6650_s_frame_interval(struct v4l2_subdev *sd,
        struct ov6650 *priv = to_ov6650(client);
        struct v4l2_fract *tpf = &ival->interval;
        int div, ret;
-       u8 clkrc;
 
        if (tpf->numerator == 0 || tpf->denominator == 0)
                div = 1;  /* Reset to full rate */
@@ -778,14 +764,9 @@ static int ov6650_s_frame_interval(struct v4l2_subdev *sd,
        else if (div > GET_CLKRC_DIV(CLKRC_DIV_MASK))
                div = GET_CLKRC_DIV(CLKRC_DIV_MASK);
 
-       tpf->numerator = div;
-       tpf->denominator = FRAME_RATE_MAX;
-
-       clkrc = to_clkrc(tpf, priv->pclk_max);
-
-       ret = ov6650_reg_rmw(client, REG_CLKRC, clkrc, CLKRC_DIV_MASK);
+       ret = ov6650_reg_rmw(client, REG_CLKRC, to_clkrc(div), CLKRC_DIV_MASK);
        if (!ret) {
-               priv->tpf.numerator = GET_CLKRC_DIV(clkrc);
+               priv->tpf.numerator = div;
                priv->tpf.denominator = FRAME_RATE_MAX;
 
                *tpf = priv->tpf;