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Commit 64f6306a authored by Wenyou Yang's avatar Wenyou Yang Committed by Mauro Carvalho Chehab
Browse files

media: atmel-isc: Add prepare and unprepare ops 



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: default avatarWenyou Yang <wenyou.yang@microchip.com>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent cab1dea3

drivers/media/platform/atmel/atmel-isc-regs.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 


/* ISC Clock Status Register */

#define ISC_CLKSR               0x00000020

#define ISC_CLKSR_SIP		BIT(31)



#define ISC_CLK(n)		BIT(n)

drivers/media/platform/atmel/atmel-isc.c

+40 −0
Original line number Diff line number Diff line
@@ -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,