Commit d898692e authored by Janusz Krzysztofik's avatar Janusz Krzysztofik Committed by Mauro Carvalho Chehab
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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: default avatarJanusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent b1c57943

drivers/media/i2c/ov6650.c

+5 −24
Original line number Diff line number Diff line
@@ -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;