media: atomisp: reduce the risk of a race condition

This driver is really on bad shape. One of the problems
is that, as soon as the I2C transfers start to happen, it
timeouts detecting a camera:

	ov2680 i2c-OVTI2680:00: ov2680_probe: ACPI detected it on bus ID=CAM1, HID=OVTI2680
	atomisp-isp2 0000:00:03.0: no camera attached or fail to detect
	ov2680 i2c-OVTI2680:00: gmin: initializing atomisp module subdev data using PMIC regulator
	...

The right fix here would be to use defer probe, but driver is
still on too bad shape.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/atomisp/pci/atomisp_v4l2.c

@@ -46,6 +46,10 @@
 
 #include "device_access.h"
 
+/* Timeouts to wait for all subdevs to be registered */
+#define SUBDEV_WAIT_TIMEOUT		50 /* ms */
+#define SUBDEV_WAIT_TIMEOUT_MAX_COUNT	40 /* up to 2 seconds */
+
 /* G-Min addition: pull this in from intel_mid_pm.h */
 #define CSTATE_EXIT_LATENCY_C1  1
 
@@ -1082,7 +1086,7 @@ static int atomisp_subdev_probe(struct atomisp_device *isp)
 {
 	const struct atomisp_platform_data *pdata;
 	struct intel_v4l2_subdev_table *subdevs;
-	int ret, raw_index = -1;
+	int ret, raw_index = -1, count;
 
 	pdata = atomisp_get_platform_data();
 	if (!pdata) {
@@ -1090,6 +1094,8 @@ static int atomisp_subdev_probe(struct atomisp_device *isp)
 		return 0;
 	}
 
+	/* FIXME: should, instead, use I2C probe */
+
 	for (subdevs = pdata->subdevs; subdevs->type; ++subdevs) {
 		struct v4l2_subdev *subdev;
 		struct i2c_board_info *board_info =
@@ -1098,6 +1104,8 @@ static int atomisp_subdev_probe(struct atomisp_device *isp)
 		    i2c_get_adapter(subdevs->v4l2_subdev.i2c_adapter_id);
 		int sensor_num, i;
 
+		dev_info(isp->dev, "Probing Subdev %s\n", board_info->type);
+
 		if (!adapter) {
 			dev_err(isp->dev,
 				"Failed to find i2c adapter for subdev %s\n",
@@ -1177,6 +1185,16 @@ static int atomisp_subdev_probe(struct atomisp_device *isp)
 		}
 	}
 
+	/* FIXME: should return -EPROBE_DEFER if not all subdevs were probed */
+	for (count = 0; count < SUBDEV_WAIT_TIMEOUT_MAX_COUNT; count++) {
+		if (isp->input_cnt)
+			break;
+		msleep(SUBDEV_WAIT_TIMEOUT);
+		count++;
+	}
+	/* Wait more time to give more time for subdev init code */
+	msleep(5 * SUBDEV_WAIT_TIMEOUT);
+
 	/*
 	 * HACK: Currently VCM belongs to primary sensor only, but correct
 	 * approach must be to acquire from platform code which sensor
@@ -1186,8 +1204,11 @@ static int atomisp_subdev_probe(struct atomisp_device *isp)
 		isp->inputs[raw_index].motor = isp->motor;
 
 	/* Proceed even if no modules detected. For COS mode and no modules. */
-	if (!isp->inputs[0].camera)
+	if (!isp->input_cnt)
 		dev_warn(isp->dev, "no camera attached or fail to detect\n");
+	else
+		dev_info(isp->dev, "detected %d camera sensors\n",
+			 isp->input_cnt);
 
 	return atomisp_csi_lane_config(isp);
 }