[media] media: ov7670: add possibility to bypass pll for ov7675

For a frame rate of 30 fps a pixclk of 24MHz is needed. For those
cases where the ov7670 has a clean 24MHz input (xvclk) the PLL
can be bypassed.
This will result in a value of clkrc of 1, which means that in practice
pixclk = xvclk (input clock)

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
index dea2917a2b12..3e503396aaa4 100644
--- a/drivers/media/i2c/ov7670.c
+++ b/drivers/media/i2c/ov7670.c
@@ -230,6 +230,7 @@ struct ov7670_info {
         int clock_speed;                /* External clock speed (MHz) */
         u8 clkrc;                       /* Clock divider value */
         bool use_smbus;                 /* Use smbus I/O instead of I2C */
+        bool pll_bypass;
         const struct ov7670_devtype *devtype; /* Device specifics */
 };
 
@@ -755,7 +756,12 @@ static void ov7675_get_framerate(struct v4l2_subdev *sd,
 {
         struct ov7670_info *info = to_state(sd);
         u32 clkrc = info->clkrc;
-        u32 pll_factor = PLL_FACTOR;
+        int pll_factor;
+
+        if (info->pll_bypass)
+                pll_factor = 1;
+        else
+                pll_factor = PLL_FACTOR;
 
         clkrc++;
         if (info->fmt->mbus_code == V4L2_MBUS_FMT_SBGGR8_1X8)
@@ -771,7 +777,7 @@ static int ov7675_set_framerate(struct v4l2_subdev *sd,
 {
         struct ov7670_info *info = to_state(sd);
         u32 clkrc;
-        u32 pll_factor = PLL_FACTOR;
+        int pll_factor;
         int ret;
 
         /*
@@ -781,6 +787,16 @@ static int ov7675_set_framerate(struct v4l2_subdev *sd,
          * pixclk = clock_speed / (clkrc + 1) * PLLfactor
          *
          */
+        if (info->pll_bypass) {
+                pll_factor = 1;
+                ret = ov7670_write(sd, REG_DBLV, DBLV_BYPASS);
+        } else {
+                pll_factor = PLL_FACTOR;
+                ret = ov7670_write(sd, REG_DBLV, DBLV_X4);
+        }
+        if (ret < 0)
+                return ret;
+
         if (tpf->numerator == 0 || tpf->denominator == 0) {
                 clkrc = 0;
         } else {
@@ -808,6 +824,7 @@ static int ov7675_set_framerate(struct v4l2_subdev *sd,
         ret = ov7670_write(sd, REG_CLKRC, info->clkrc);
         if (ret < 0)
                 return ret;
+
         return ov7670_write(sd, REG_DBLV, DBLV_X4);
 }
 
@@ -1688,6 +1705,13 @@ static int ov7670_probe(struct i2c_client *client,
 
                 if (config->clock_speed)
                         info->clock_speed = config->clock_speed;
+
+                /*
+                 * It should be allowed for ov7670 too when it is migrated to
+                 * the new frame rate formula.
+                 */
+                if (config->pll_bypass && id->driver_data != MODEL_OV7670)
+                        info->pll_bypass = true;
         }
 
         /* Make sure it's an ov7670 */