When the input clock frequency is out of bounds for the PLL, bypass the
PLL and just divide the input clock to achieve the requested output
frequency.
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
drivers/media/i2c/mt9p031.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
index 14a616e..5483ab2 100644
--- a/drivers/media/i2c/mt9p031.c
+++ b/drivers/media/i2c/mt9p031.c
@@ -78,6 +78,9 @@
#define MT9P031_PLL_CONFIG_1 0x11
#define MT9P031_PLL_CONFIG_2 0x12
#define MT9P031_PIXEL_CLOCK_CONTROL 0x0a
+#define MT9P031_PIXEL_CLOCK_INVERT (1 << 15)
+#define MT9P031_PIXEL_CLOCK_SHIFT(n) ((n) << 8)
+#define MT9P031_PIXEL_CLOCK_DIVIDE(n) ((n) << 0)
#define MT9P031_FRAME_RESTART 0x0b
#define MT9P031_SHUTTER_DELAY 0x0c
#define MT9P031_RST 0x0d
@@ -130,6 +133,8 @@ struct mt9p031 {
enum mt9p031_model model;
struct aptina_pll pll;
+ unsigned int clk_div;
+ bool use_pll;
int reset;
struct v4l2_ctrl_handler ctrls;
@@ -198,6 +203,11 @@ static int mt9p031_reset(struct mt9p031 *mt9p031)
if (ret < 0)
return ret;
+ ret = mt9p031_write(client, MT9P031_PIXEL_CLOCK_CONTROL,
+ MT9P031_PIXEL_CLOCK_DIVIDE(mt9p031->clk_div));
+ if (ret < 0)
+ return ret;
+
return mt9p031_set_output_control(mt9p031, MT9P031_OUTPUT_CONTROL_CEN,
0);
}
@@ -232,8 +242,24 @@ static int mt9p031_clk_setup(struct mt9p031 *mt9p031)
if (ret < 0)
return ret;
+ /* If the external clock frequency is out of bounds for the PLL use the
+ * pixel clock divider only and disable the PLL.
+ */
+ if (pdata->ext_freq > limits.ext_clock_max) {
+ unsigned int div;
+
+ div = DIV_ROUND_UP(pdata->ext_freq, pdata->target_freq);
+ div = roundup_pow_of_two(div) / 2;
+
+ mt9p031->clk_div = max_t(unsigned int, div, 64);
+ mt9p031->use_pll = false;
+
+ return 0;
+ }
+
mt9p031->pll.ext_clock = pdata->ext_freq;
mt9p031->pll.pix_clock = pdata->target_freq;
+ mt9p031->use_pll = true;
return aptina_pll_calculate(&client->dev, &limits, &mt9p031->pll);
}
@@ -243,6 +269,9 @@ static int mt9p031_pll_enable(struct mt9p031 *mt9p031)
struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
int ret;
+ if (!mt9p031->use_pll)
+ return 0;
+
ret = mt9p031_write(client, MT9P031_PLL_CONTROL,
MT9P031_PLL_CONTROL_PWRON);
if (ret < 0)
@@ -268,6 +297,9 @@ static inline int mt9p031_pll_disable(struct mt9p031 *mt9p031)
{
struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev);
+ if (!mt9p031->use_pll)
+ return 0;
+
return mt9p031_write(client, MT9P031_PLL_CONTROL,
MT9P031_PLL_CONTROL_PWROFF);
}
--
1.8.3.2
--
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