Commit 71a5f1b9 authored by Ioannis Karachalios's avatar Ioannis Karachalios Committed by Anas Nashif
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drivers: display: smartbond: Optimize driver PM 



This commit should optimize the way the device is allowed
to enter the suspended state. Instead of returning a PM
error code to abort the PM process, the standby power state
is constrained as long as the device is not allowed to enter
suspension. With that approach, acquiring PD_SYS is not needed
when in PM device runtime mode.

Signed-off-by: default avatarIoannis Karachalios <ioannis.karachalios.px@renesas.com>
parent 2958f691

drivers/display/display_renesas_lcdc.c

+30 −22
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <zephyr/linker/devicetree_regions.h>

#include <zephyr/pm/device.h>

#include <zephyr/pm/device_runtime.h>

#include <zephyr/pm/policy.h>



#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(smartbond_display, CONFIG_DISPLAY_LOG_LEVEL);
@@ -75,8 +76,7 @@ struct display_smartbond_data { 
	/* Granted DMA channel used for memory transfers */

	int dma_channel;

#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

	/* Flag to determine if device suspension is allowed */

	bool is_sleep_allowed;

	ATOMIC_DEFINE(pm_policy_state_flag, 1);

#endif

};
@@ -99,6 +99,29 @@ struct display_smartbond_config { 
	enum display_pixel_format pixel_format;

};



static inline void lcdc_smartbond_pm_policy_state_lock_get(struct display_smartbond_data *data)

{

#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

	if (atomic_test_and_set_bit(data->pm_policy_state_flag, 0) == 0) {

		/*

		 * Prevent the SoC from etering the normal sleep state as PDC does not support

		 * waking up the application core following LCDC events.

		 */

		pm_policy_state_lock_get(PM_STATE_STANDBY, PM_ALL_SUBSTATES);

	}

#endif

}



static inline void lcdc_smartbond_pm_policy_state_lock_put(struct display_smartbond_data *data)

{

#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

	if (atomic_test_and_clear_bit(data->pm_policy_state_flag, 0) == 1) {

		/* Allow the SoC to enter the nornmal sleep state once LCDC is inactive */

		pm_policy_state_lock_put(PM_STATE_STANDBY, PM_ALL_SUBSTATES);

	}

#endif

}



/* Display pixel to layer color format translation */

static uint8_t lcdc_smartbond_pixel_to_lcm(enum display_pixel_format pixel_format)

{
@@ -319,11 +342,6 @@ static int display_smartbond_init(const struct device *dev) 
	pm_device_init_suspended(dev);



	ret = pm_device_runtime_enable(dev);



	/* Sleep is allowed until the device is explicitly resumed on application level. */

	if (ret == 0) {

		data->is_sleep_allowed = true;

	}

#else

	/* Resume if either PM is not used at all or if PM without runtime is used. */

	ret = display_smartbond_resume(dev);
@@ -355,13 +373,11 @@ static int display_smartbond_blanking_on(const struct device *dev) 
		}

	}



#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

	/*

	 * At this moment the display panel should be turned off and so the device

	 * can enter the suspend state.

	 */

	data->is_sleep_allowed = true;

#endif

	lcdc_smartbond_pm_policy_state_lock_put(data);



	k_sem_give(&data->device_sem);
@@ -391,13 +407,11 @@ static int display_smartbond_blanking_off(const struct device *dev) 
	 */

	LCDC->LCDC_MODE_REG &= ~LCDC_LCDC_MODE_REG_LCDC_FORCE_BLANK_Msk;



#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

	/*

	 * At this moment the display should be turned on and so the device

	 * cannot enter the suspend state.

	 */

	data->is_sleep_allowed = false;

#endif

	lcdc_smartbond_pm_policy_state_lock_get(data);



	k_sem_give(&data->device_sem);
@@ -566,20 +580,14 @@ static int display_smartbond_write(const struct device *dev, 
#if defined(CONFIG_PM_DEVICE) || defined(CONFIG_PM_DEVICE_RUNTIME)

static int display_smartbond_pm_action(const struct device *dev, enum pm_device_action action)

{

	/* Initialize with an error code that should abort sleeping */

	int ret = -EBUSY;

	struct display_smartbond_data *data = dev->data;

	int ret = 0;



	switch (action) {

	case PM_DEVICE_ACTION_SUSPEND:

		/* Sleep is only allowed whne display blanking is activated */

		if (data->is_sleep_allowed) {

		/* A non-zero value should not affect sleep */

		(void)display_smartbond_suspend(dev);

			ret = 0;

		}

		break;

	case PM_DEVICE_ACTION_RESUME:

		__ASSERT_NO_MSG(data->is_sleep_allowed);

		/*

		 * The resume error code should not be taken into consideration

		 * by the PM subsystem

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