V4L/DVB (5691): Ov7670: reset clkrc in rgb565 mode

A bug in the ov7670 sensor causes it to introduce noise unless the CLKRC
register is rewritten *after* setting the image mode.  Naturally,
resetting CLKRC in this way will cause other modes to fail.  So
carefully poke the register only when indicated.

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

diff --git a/drivers/media/video/ov7670.c b/drivers/media/video/ov7670.c
index 03bc369..3ceb8a6 100644 (file)
--- a/drivers/media/video/ov7670.c
+++ b/drivers/media/video/ov7670.c
@@ -720,12 +720,22 @@ static int ov7670_s_fmt(struct i2c_client *c, struct v4l2_format *fmt)
        struct ov7670_format_struct *ovfmt;
        struct ov7670_win_size *wsize;
        struct ov7670_info *info = i2c_get_clientdata(c);
-       unsigned char com7;
+       unsigned char com7, clkrc;
 
        ret = ov7670_try_fmt(c, 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(c, 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
@@ -744,7 +754,10 @@ static int ov7670_s_fmt(struct i2c_client *c, struct v4l2_format *fmt)
        if (wsize->regs)
                ret = ov7670_write_array(c, wsize->regs);
        info->fmt = ovfmt;
-       return 0;
+
+       if (fmt->fmt.pix.pixelformat == V4L2_PIX_FMT_RGB565 && ret == 0)
+               ret = ov7670_write(c, REG_CLKRC, clkrc);
+       return ret;
 }
 
 /*
@@ -1267,7 +1280,9 @@ static int ov7670_attach(struct i2c_adapter *adapter)
        ret = ov7670_detect(client);
        if (ret)
                goto out_free_info;
-       i2c_attach_client(client);
+       ret = i2c_attach_client(client);
+       if (ret)
+               goto out_free_info;
        return 0;
 
   out_free_info: