V4L/DVB: ov7670: Avoid reading clkrc

Reading the clkrc register creates flaky behavior in some situations, and
we can easily track its state separately.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 18 insertions, 27 deletions

diff --git a/drivers/media/video/ov7670.c b/drivers/media/video/ov7670.c
index b44762adb1e9..b2e6f8e730a3 100644
--- a/drivers/media/video/ov7670.c
+++ b/drivers/media/video/ov7670.c
@@ -198,6 +198,7 @@ struct ov7670_info {
         struct ov7670_format_struct *fmt;  /* Current format */
         unsigned char sat;              /* Saturation value */
         int hue;                        /* Hue value */
+        u8 clkrc;                       /* Clock divider value */
 };
 
 static inline struct ov7670_info *to_state(struct v4l2_subdev *sd)
@@ -744,22 +745,12 @@ static int ov7670_s_fmt(struct v4l2_subdev *sd, struct v4l2_format *fmt)
         struct ov7670_format_struct *ovfmt;
         struct ov7670_win_size *wsize;
         struct ov7670_info *info = to_state(sd);
-        unsigned char com7, clkrc = 0;
+        unsigned char com7;
 
         ret = ov7670_try_fmt_internal(sd, fmt, &ovfmt, &wsize);
         if (ret)
                 return ret;
         /*
-         * HACK: if we're running rgb565 we need to grab then rewrite
-         * CLKRC.  If we're *not*, however, then rewriting clkrc hoses
-         * the colors.
-         */
-        if (fmt->fmt.pix.pixelformat == V4L2_PIX_FMT_RGB565) {
-                ret = ov7670_read(sd, REG_CLKRC, &clkrc);
-                if (ret)
-                        return ret;
-        }
-        /*
          * COM7 is a pain in the ass, it doesn't like to be read then
          * quickly written afterward.  But we have everything we need
          * to set it absolutely here, as long as the format-specific
@@ -779,8 +770,14 @@ static int ov7670_s_fmt(struct v4l2_subdev *sd, struct v4l2_format *fmt)
                 ret = ov7670_write_array(sd, wsize->regs);
         info->fmt = ovfmt;
 
+        /*
+         * If we're running RGB565, we must rewrite clkrc after setting
+         * the other parameters or the image looks poor.  If we're *not*
+         * doing RGB565, we must not rewrite clkrc or the image looks
+         * *really* poor.
+         */
         if (fmt->fmt.pix.pixelformat == V4L2_PIX_FMT_RGB565 && ret == 0)
-                ret = ov7670_write(sd, REG_CLKRC, clkrc);
+                ret = ov7670_write(sd, REG_CLKRC, info->clkrc);
         return ret;
 }
 
@@ -791,20 +788,17 @@ static int ov7670_s_fmt(struct v4l2_subdev *sd, struct v4l2_format *fmt)
 static int ov7670_g_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
 {
         struct v4l2_captureparm *cp = &parms->parm.capture;
-        unsigned char clkrc;
-        int ret;
+        struct ov7670_info *info = to_state(sd);
 
         if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                 return -EINVAL;
-        ret = ov7670_read(sd, REG_CLKRC, &clkrc);
-        if (ret < 0)
-                return ret;
+
         memset(cp, 0, sizeof(struct v4l2_captureparm));
         cp->capability = V4L2_CAP_TIMEPERFRAME;
         cp->timeperframe.numerator = 1;
         cp->timeperframe.denominator = OV7670_FRAME_RATE;
-        if ((clkrc & CLK_EXT) == 0 && (clkrc & CLK_SCALE) > 1)
-                cp->timeperframe.denominator /= (clkrc & CLK_SCALE);
+        if ((info->clkrc & CLK_EXT) == 0 && (info->clkrc & CLK_SCALE) > 1)
+                cp->timeperframe.denominator /= (info->clkrc & CLK_SCALE);
         return 0;
 }
 
@@ -812,6 +806,7 @@ static int ov7670_s_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
 {
         struct v4l2_captureparm *cp = &parms->parm.capture;
         struct v4l2_fract *tpf = &cp->timeperframe;
+        struct ov7670_info *info = to_state(sd);
         unsigned char clkrc;
         int ret, div;
 
@@ -819,12 +814,7 @@ static int ov7670_s_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
                 return -EINVAL;
         if (cp->extendedmode != 0)
                 return -EINVAL;
-        /*
-         * CLKRC has a reserved bit, so let's preserve it.
-         */
-        ret = ov7670_read(sd, REG_CLKRC, &clkrc);
-        if (ret < 0)
-                return ret;
+
         if (tpf->numerator == 0 || tpf->denominator == 0)
                 div = 1;  /* Reset to full rate */
         else
@@ -833,10 +823,10 @@ static int ov7670_s_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
                 div = 1;
         else if (div > CLK_SCALE)
                 div = CLK_SCALE;
-        clkrc = (clkrc & 0x80) | div;
+        info->clkrc = (info->clkrc & 0x80) | div;
         tpf->numerator = 1;
         tpf->denominator = OV7670_FRAME_RATE/div;
-        return ov7670_write(sd, REG_CLKRC, clkrc);
+        return ov7670_write(sd, REG_CLKRC, info->clkrc);
 }
 
 
@@ -1268,6 +1258,7 @@ static int ov7670_probe(struct i2c_client *client,
 
         info->fmt = &ov7670_formats[0];
         info->sat = 128;        /* Review this */
+        info->clkrc = 1;        /* 30fps */
 
         return 0;
 }