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media: atmel-isc: Add prepare and unprepare ops

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A software write operation to the ISC_CLKEN or ISC_CLKDIS register
requires double clock domain synchronization and is not permitted
when the ISC_SR.SIP is asserted. So add the .prepare and .unprepare
ops to make sure the ISC_CLKSR.SIP is unasserted before the write
operation to the ISC_CLKEN or ISC_CLKDIS register.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Wenyou Yang 2017-10-10 04:46:37 +02:00 committed by Mauro Carvalho Chehab
parent cab1dea3be
commit 64f6306a5a
2 changed files with 41 additions and 0 deletions
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1
drivers/media/platform/atmel/atmel-isc-regs.h
View File

@ -42,6 +42,7 @@
/* ISC Clock Status Register */
#define ISC_CLKSR 0x00000020
#define ISC_CLKSR_SIP BIT(31)
#define ISC_CLK(n) BIT(n)

40
drivers/media/platform/atmel/atmel-isc.c
View File

@ -308,6 +308,44 @@ module_param(sensor_preferred, uint, 0644);
MODULE_PARM_DESC(sensor_preferred,
"Sensor is preferred to output the specified format (1-on 0-off), default 1");
static int isc_wait_clk_stable(struct clk_hw *hw)
{
struct isc_clk *isc_clk = to_isc_clk(hw);
struct regmap *regmap = isc_clk->regmap;
unsigned long timeout = jiffies + usecs_to_jiffies(1000);
unsigned int status;
while (time_before(jiffies, timeout)) {
regmap_read(regmap, ISC_CLKSR, &status);
if (!(status & ISC_CLKSR_SIP))
return 0;
usleep_range(10, 250);
}
return -ETIMEDOUT;
}
static int isc_clk_prepare(struct clk_hw *hw)
{
struct isc_clk *isc_clk = to_isc_clk(hw);
if (isc_clk->id == ISC_MCK)
pm_runtime_get_sync(isc_clk->dev);
return isc_wait_clk_stable(hw);
}
static void isc_clk_unprepare(struct clk_hw *hw)
{
struct isc_clk *isc_clk = to_isc_clk(hw);
isc_wait_clk_stable(hw);
if (isc_clk->id == ISC_MCK)
pm_runtime_put_sync(isc_clk->dev);
}
static int isc_clk_enable(struct clk_hw *hw)
{
struct isc_clk *isc_clk = to_isc_clk(hw);
@ -459,6 +497,8 @@ static int isc_clk_set_rate(struct clk_hw *hw,
}
static const struct clk_ops isc_clk_ops = {
.prepare = isc_clk_prepare,
.unprepare = isc_clk_unprepare,
.enable = isc_clk_enable,
.disable = isc_clk_disable,
.is_enabled = isc_clk_is_enabled,