media: ccs: Hardware requires a delay after starting the clock of lif…

…ting 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 <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]>
mrcsosa · Jan 12, 2021 · 2fed6c8 · 2fed6c8
1 parent 51fc72e
commit 2fed6c8
Showing 1 changed file with 16 additions and 13 deletions.
diff --git a/drivers/media/i2c/ccs/ccs-core.c b/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.