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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>
This commit is contained in:
Sakari Ailus 2020-10-08 18:24:39 +02:00 committed by Mauro Carvalho Chehab
parent 51fc72e541
commit 2fed6c84dc
1 changed files with 18 additions and 15 deletions
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33
drivers/media/i2c/ccs/ccs-core.c
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@ -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),
@ -1525,22 +1524,26 @@ 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);
if (ccsdev->flags & CCS_DEVICE_FLAG_IS_SMIA)
sleep = SMIAPP_RESET_DELAY(sensor->hwcfg.ext_clk);
else
sleep = 5000;
usleep_range(sleep, sleep);
}
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;
usleep_range(sleep, sleep);
/*
* Failures to respond to the address change command have been noticed.
* Those failures seem to be caused by the sensor requiring a longer