[PATCH 4/4] media: ov5640: reduce rate according to maximum pixel clock frequency

[Hugues Fruchet]

Reduce parallel port rate according to maximum pixel clock frequency
admissible by camera interface.
This allows to support any resolutions/framerate requests by decreasing
the framerate according to maximum camera interface capabilities.

Signed-off-by: Hugues Fruchet <hugues.fruc...@st.com>
---
 drivers/media/i2c/ov5640.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
index da4d754..9f3c32e 100644
--- a/drivers/media/i2c/ov5640.c
+++ b/drivers/media/i2c/ov5640.c
@@ -918,6 +918,8 @@ static int ov5640_set_dvp_pclk(struct ov5640_dev *sensor,
 {
        u8 prediv, mult, sysdiv, pll_rdiv, bit_div, pclk_div;
        int ret;
+       struct i2c_client *client = sensor->i2c_client;
+       unsigned int pclk_freq, max_pclk_freq;
        /*
         * FIXME, value of PCLK divider deduced from
         * mode registers hardcoded sequence and tests
@@ -941,6 +943,16 @@ static int ov5640_set_dvp_pclk(struct ov5640_dev *sensor,
        if (ret)
                return ret;
 
+       pclk_freq = rate / dvp_pclk_divider;
+       max_pclk_freq = sensor->ep.bus.parallel.pclk_max_frequency;
+
+       /* clip rate according to optional maximum pixel clock limit */
+       if (max_pclk_freq && pclk_freq > max_pclk_freq) {
+               rate = max_pclk_freq * dvp_pclk_divider;
+               dev_dbg(&client->dev, "DVP pixel clock too high (%d > %d Hz), 
reducing rate...\n",
+                       pclk_freq, max_pclk_freq);
+       }
+
        ov5640_calc_pclk(sensor, rate, &prediv, &mult, &sysdiv, &pll_rdiv,
                         &bit_div, &pclk_div);
 
-- 
2.7.4