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Subject[PATCH v10 5/7] ov5670: Support probe whilst the device is in a low power state
Date
Tell ACPI device PM code that the driver supports the device being in a
low power state when the driver's probe function is entered.

Also do identification on the first access of the device, whether in probe
or when starting streaming.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
---
drivers/media/i2c/ov5670.c | 76 +++++++++++++++++++++++---------------
1 file changed, 46 insertions(+), 30 deletions(-)

diff --git a/drivers/media/i2c/ov5670.c b/drivers/media/i2c/ov5670.c
index 866c8c2e8f59a..eb0d599f3318b 100644
--- a/drivers/media/i2c/ov5670.c
+++ b/drivers/media/i2c/ov5670.c
@@ -1832,6 +1832,8 @@ struct ov5670 {

/* Streaming on/off */
bool streaming;
+ /* True if the device has been identified */
+ bool identified;
};

#define to_ov5670(_sd) container_of(_sd, struct ov5670, sd)
@@ -2271,6 +2273,32 @@ static int ov5670_get_skip_frames(struct v4l2_subdev *sd, u32 *frames)
return 0;
}

+/* Verify chip ID */
+static int ov5670_identify_module(struct ov5670 *ov5670)
+{
+ struct i2c_client *client = v4l2_get_subdevdata(&ov5670->sd);
+ int ret;
+ u32 val;
+
+ if (ov5670->identified)
+ return 0;
+
+ ret = ov5670_read_reg(ov5670, OV5670_REG_CHIP_ID,
+ OV5670_REG_VALUE_24BIT, &val);
+ if (ret)
+ return ret;
+
+ if (val != OV5670_CHIP_ID) {
+ dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
+ OV5670_CHIP_ID, val);
+ return -ENXIO;
+ }
+
+ ov5670->identified = true;
+
+ return 0;
+}
+
/* Prepare streaming by writing default values and customized values */
static int ov5670_start_streaming(struct ov5670 *ov5670)
{
@@ -2279,6 +2307,10 @@ static int ov5670_start_streaming(struct ov5670 *ov5670)
int link_freq_index;
int ret;

+ ret = ov5670_identify_module(ov5670);
+ if (ret)
+ return ret;
+
/* Get out of from software reset */
ret = ov5670_write_reg(ov5670, OV5670_REG_SOFTWARE_RST,
OV5670_REG_VALUE_08BIT, OV5670_SOFTWARE_RST);
@@ -2400,27 +2432,6 @@ static int __maybe_unused ov5670_resume(struct device *dev)
return 0;
}

-/* Verify chip ID */
-static int ov5670_identify_module(struct ov5670 *ov5670)
-{
- struct i2c_client *client = v4l2_get_subdevdata(&ov5670->sd);
- int ret;
- u32 val;
-
- ret = ov5670_read_reg(ov5670, OV5670_REG_CHIP_ID,
- OV5670_REG_VALUE_24BIT, &val);
- if (ret)
- return ret;
-
- if (val != OV5670_CHIP_ID) {
- dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
- OV5670_CHIP_ID, val);
- return -ENXIO;
- }
-
- return 0;
-}
-
static const struct v4l2_subdev_video_ops ov5670_video_ops = {
.s_stream = ov5670_set_stream,
};
@@ -2455,6 +2466,7 @@ static int ov5670_probe(struct i2c_client *client)
struct ov5670 *ov5670;
const char *err_msg;
u32 input_clk = 0;
+ bool low_power;
int ret;

device_property_read_u32(&client->dev, "clock-frequency", &input_clk);
@@ -2471,11 +2483,14 @@ static int ov5670_probe(struct i2c_client *client)
/* Initialize subdev */
v4l2_i2c_subdev_init(&ov5670->sd, client, &ov5670_subdev_ops);

- /* Check module identity */
- ret = ov5670_identify_module(ov5670);
- if (ret) {
- err_msg = "ov5670_identify_module() error";
- goto error_print;
+ low_power = acpi_dev_state_low_power(&client->dev);
+ if (!low_power) {
+ /* Check module identity */
+ ret = ov5670_identify_module(ov5670);
+ if (ret) {
+ err_msg = "ov5670_identify_module() error";
+ goto error_print;
+ }
}

mutex_init(&ov5670->mutex);
@@ -2512,10 +2527,10 @@ static int ov5670_probe(struct i2c_client *client)
ov5670->streaming = false;

/*
- * Device is already turned on by i2c-core with ACPI domain PM.
- * Enable runtime PM and turn off the device.
+ * Don't set the device's state to active if it's in a low power state.
*/
- pm_runtime_set_active(&client->dev);
+ if (!low_power)
+ pm_runtime_set_active(&client->dev);
pm_runtime_enable(&client->dev);
pm_runtime_idle(&client->dev);

@@ -2557,7 +2572,7 @@ static const struct dev_pm_ops ov5670_pm_ops = {

#ifdef CONFIG_ACPI
static const struct acpi_device_id ov5670_acpi_ids[] = {
- {"INT3479"},
+ { "INT3479" },
{ /* sentinel */ }
};

@@ -2572,6 +2587,7 @@ static struct i2c_driver ov5670_i2c_driver = {
},
.probe_new = ov5670_probe,
.remove = ov5670_remove,
+ .flags = I2C_DRV_FL_ALLOW_LOW_POWER_PROBE,
};

module_i2c_driver(ov5670_i2c_driver);
--
2.20.1
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