media: ccs: Hardware requires a delay after starting the clock of lifting reset

A CCS compliant device requires a delay before the first I²C transaction
after pulling xshutdown up or starting the external clock. This is what
the driver does. However, if neither is actually there, there's no need
for the delay.

This also has the effect of removing an unnecessary delay on ACPI systems
where ACPI is responsible for the power-up sequence.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/ccs/ccs-core.c

@@ -1515,7 +1515,6 @@ static int ccs_power_on(struct device *dev)
 	struct ccs_sensor *sensor =
 		container_of(ssd, struct ccs_sensor, ssds[0]);
 	const struct ccs_device *ccsdev = device_get_match_data(dev);
-	unsigned int sleep;
 	int rval;
 
 	rval = regulator_bulk_enable(ARRAY_SIZE(ccs_regulators),
@@ -1525,21 +1524,25 @@ static int ccs_power_on(struct device *dev)
 		return rval;
 	}
 
-	rval = clk_prepare_enable(sensor->ext_clk);
-	if (rval < 0) {
-		dev_dbg(dev, "failed to enable xclk\n");
-		goto out_xclk_fail;
-	}
+	if (sensor->reset || sensor->xshutdown || sensor->ext_clk) {
+		unsigned int sleep;
+
+		rval = clk_prepare_enable(sensor->ext_clk);
+		if (rval < 0) {
+			dev_dbg(dev, "failed to enable xclk\n");
+			goto out_xclk_fail;
+		}
 
-	gpiod_set_value(sensor->reset, 0);
-	gpiod_set_value(sensor->xshutdown, 1);
+		gpiod_set_value(sensor->reset, 0);
+		gpiod_set_value(sensor->xshutdown, 1);
 
-	if (ccsdev->flags & CCS_DEVICE_FLAG_IS_SMIA)
-		sleep = SMIAPP_RESET_DELAY(sensor->hwcfg.ext_clk);
-	else
-		sleep = 5000;
+		if (ccsdev->flags & CCS_DEVICE_FLAG_IS_SMIA)
+			sleep = SMIAPP_RESET_DELAY(sensor->hwcfg.ext_clk);
+		else
+			sleep = 5000;
 
-	usleep_range(sleep, sleep);
+		usleep_range(sleep, sleep);
+	}
 
 	/*
 	 * Failures to respond to the address change command have been noticed.