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Subject[v2 3/3] media: ov8856: Implement sensor module revision identification
Date
Query the sensor for its module revision, and compare it
to known revisions.
Currently only the '1B' revision has been added.

Signed-off-by: Robert Foss <robert.foss@linaro.org>
---
drivers/media/i2c/ov8856.c | 54 +++++++++++++++++++++++++++++++++-----
1 file changed, 48 insertions(+), 6 deletions(-)

diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
index db61eed223e8..39662d3d86dd 100644
--- a/drivers/media/i2c/ov8856.c
+++ b/drivers/media/i2c/ov8856.c
@@ -34,6 +34,18 @@
#define OV8856_MODE_STANDBY 0x00
#define OV8856_MODE_STREAMING 0x01

+/* define 1B module revision */
+#define OV8856_1B_MODULE 0x02
+
+/* the OTP read-out buffer is at 0x7000 and 0xf is the offset
+ * of the byte in the OTP that means the module revision
+ */
+#define OV8856_MODULE_REVISION 0x700f
+#define OV8856_OTP_MODE_CTRL 0x3d84
+#define OV8856_OTP_LOAD_CTRL 0x3d81
+#define OV8856_OTP_MODE_AUTO 0x00
+#define OV8856_OTP_LOAD_CTRL_ENABLE BIT(0)
+
/* vertical-timings from sensor */
#define OV8856_REG_VTS 0x380e
#define OV8856_VTS_MAX 0x7fff
@@ -711,6 +723,25 @@ static int ov8856_test_pattern(struct ov8856 *ov8856, u32 pattern)
OV8856_REG_VALUE_08BIT, pattern);
}

+static int ov8856_check_revision(struct ov8856 *ov8856)
+{
+ int ret;
+
+ ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
+ OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
+ if (ret)
+ return ret;
+
+ ret = ov8856_write_reg(ov8856, OV8856_OTP_MODE_CTRL,
+ OV8856_REG_VALUE_08BIT, OV8856_OTP_MODE_AUTO);
+ if (ret)
+ return ret;
+
+ return ov8856_write_reg(ov8856, OV8856_OTP_LOAD_CTRL,
+ OV8856_REG_VALUE_08BIT,
+ OV8856_OTP_LOAD_CTRL_ENABLE);
+}
+
static int ov8856_set_ctrl(struct v4l2_ctrl *ctrl)
{
struct ov8856 *ov8856 = container_of(ctrl->handler,
@@ -1144,6 +1175,23 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
return -ENXIO;
}

+ /* check sensor hardware revision */
+ ret = ov8856_check_revision(ov8856);
+ if (ret) {
+ dev_err(&client->dev, "failed to check sensor revision");
+ return ret;
+ }
+
+ ret = ov8856_read_reg(ov8856, OV8856_MODULE_REVISION,
+ OV8856_REG_VALUE_08BIT, &val);
+ if (ret)
+ return ret;
+
+ dev_info(&client->dev, "OV8856 revision %x (%s) at address 0x%02x\n",
+ val,
+ val == OV8856_1B_MODULE ? "1B" : "unknown revision",
+ client->addr);
+
return 0;
}

@@ -1254,12 +1302,6 @@ static int ov8856_probe(struct i2c_client *client)
return PTR_ERR(ov8856->xvclk);
}

- ret = clk_set_rate(ov8856->xvclk, OV8856_XVCLK_24);
- if (ret < 0) {
- dev_err(&client->dev, "failed to set xvclk rate (24MHz)\n");
- return ret;
- }
-
ov8856->reset_gpio = devm_gpiod_get(&client->dev, "reset",
GPIOD_OUT_HIGH);
if (IS_ERR(ov8856->reset_gpio)) {
--
2.20.1
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