From 2fed6c84dc6fb9e374466d8a0ba86eb6ca7868f8 Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Thu, 8 Oct 2020 18:24:39 +0200 Subject: [PATCH] media: ccs: Hardware requires a delay after starting the clock of lifting reset MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/i2c/ccs/ccs-core.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c index e1b3c56..fae8ced 100644 --- 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. -- 2.7.4