drivers: display: mcux_elcdif: enable directly writing framebuffer
Enable the ELCDIF driver to directly write the framebuffer using
hardware, when an entire framebuffer update is requested. This will
enable better performance for applications that avoid partial
display updates.
Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>
diff --git a/drivers/display/Kconfig.mcux_elcdif b/drivers/display/Kconfig.mcux_elcdif
index 58b6ba0..3531b0f 100644
--- a/drivers/display/Kconfig.mcux_elcdif
+++ b/drivers/display/Kconfig.mcux_elcdif
@@ -1,4 +1,4 @@
-# Copyright (c) 2019, NXP
+# Copyright 2019,2023 NXP
# Copyright (c) 2022, Basalte bv
# SPDX-License-Identifier: Apache-2.0
@@ -12,10 +12,24 @@
if DISPLAY_MCUX_ELCDIF
-config MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
- bool "Double framebuffer"
- default y
+config MCUX_ELCDIF_FB_NUM
+ int "Framebuffers to allocate in driver"
+ default 2
+ range 0 2
help
- Optionally use two framebuffers and alternate between them.
+ Number of framebuffers to allocate in ELCDIF driver. Driver allocated
+ framebuffers are required to support partial display updates.
+ The driver has been validated to support 0 through 2 framebuffers.
+ Note that hardware will likely perform best if zero driver
+ framebuffers are allocated by the driver, and the application
+ implements double framebuffering by always calling display_write with
+ a buffer equal in size to the connected panel.
+
+ NOTE: when no framebuffers are allocated, the ELCDIF will be
+ set to display an empty buffer during initialization. This means
+ the display will show what is effectively a dump of
+ system RAM until a new framebuffer is written. If the security
+ implications of this concern you, leave at least one driver
+ framebuffer enabled.
endif # DISPLAY_MCUX_ELCDIF
diff --git a/drivers/display/display_mcux_elcdif.c b/drivers/display/display_mcux_elcdif.c
index 9cdf98a..c3d3055 100644
--- a/drivers/display/display_mcux_elcdif.c
+++ b/drivers/display/display_mcux_elcdif.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2019-22, NXP
+ * Copyright 2019-23, NXP
* Copyright (c) 2022, Basalte bv
*
* SPDX-License-Identifier: Apache-2.0
@@ -22,12 +22,6 @@
LOG_MODULE_REGISTER(display_mcux_elcdif, CONFIG_DISPLAY_LOG_LEVEL);
-#ifdef CONFIG_MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
-#define MCUX_ELCDIF_FB_NUM 2
-#else
-#define MCUX_ELCDIF_FB_NUM 1
-#endif
-
struct mcux_elcdif_config {
LCDIF_Type *base;
void (*irq_config_func)(const struct device *dev);
@@ -37,13 +31,17 @@
size_t fb_bytes;
const struct pinctrl_dev_config *pincfg;
const struct gpio_dt_spec backlight_gpio;
+ uint8_t *fb_ptr;
};
struct mcux_elcdif_data {
- uint8_t *fb_ptr;
- uint8_t *fb[MCUX_ELCDIF_FB_NUM];
+ /* Pointer to active framebuffer */
+ const uint8_t *active_fb;
+ /* Pointers to driver allocated framebuffers */
+ uint8_t *fb[CONFIG_MCUX_ELCDIF_FB_NUM];
struct k_sem sem;
- uint8_t write_idx;
+ /* Tracks index of next active driver framebuffer */
+ uint8_t next_idx;
};
static int mcux_elcdif_write(const struct device *dev, const uint16_t x,
@@ -53,9 +51,6 @@
{
const struct mcux_elcdif_config *config = dev->config;
struct mcux_elcdif_data *dev_data = dev->data;
-
- uint8_t write_idx = (dev_data->write_idx + 1) % MCUX_ELCDIF_FB_NUM;
-
int h_idx;
const uint8_t *src;
uint8_t *dst;
@@ -65,39 +60,65 @@
LOG_DBG("W=%d, H=%d, @%d,%d", desc->width, desc->height, x, y);
-#ifdef CONFIG_MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
- k_sem_take(&dev_data->sem, K_FOREVER);
- memcpy(dev_data->fb[write_idx], dev_data->fb[dev_data->write_idx],
- config->fb_bytes);
-#else
- /* wait for the next frame done */
- k_sem_reset(&dev_data->sem);
- k_sem_take(&dev_data->sem, K_FOREVER);
-#endif
+ if ((x == 0) && (y == 0) &&
+ (desc->width == config->rgb_mode.panelWidth) &&
+ (desc->height == config->rgb_mode.panelHeight) &&
+ (desc->pitch == desc->width)) {
+ /* We can use the display buffer directly, no need to copy it */
+ LOG_DBG("Setting FB from %p->%p",
+ (void *) dev_data->active_fb, (void *) buf);
+ dev_data->active_fb = buf;
+ } else {
+ /* We must use partial framebuffer copy */
+ if (CONFIG_MCUX_ELCDIF_FB_NUM == 0) {
+ LOG_ERR("Partial display refresh requires driver framebuffers");
+ return -ENOTSUP;
+ } else if (dev_data->active_fb != dev_data->fb[dev_data->next_idx]) {
+ /*
+ * We must copy the entire current framebuffer to new
+ * buffer, since we wil change the active buffer
+ * address
+ */
+ src = dev_data->active_fb;
+ dst = dev_data->fb[dev_data->next_idx];
+ memcpy(dst, src, config->fb_bytes);
+ }
+ /* Now, write the display update into active framebuffer */
+ src = buf;
+ dst = dev_data->fb[dev_data->next_idx];
+ dst += config->pixel_bytes * (y * config->rgb_mode.panelWidth + x);
- src = buf;
- dst = dev_data->fb[write_idx];
- dst += config->pixel_bytes * (y * config->rgb_mode.panelWidth + x);
+ for (h_idx = 0; h_idx < desc->height; h_idx++) {
+ memcpy(dst, src, config->pixel_bytes * desc->width);
+ src += config->pixel_bytes * desc->pitch;
+ dst += config->pixel_bytes * config->rgb_mode.panelWidth;
+ }
- for (h_idx = 0; h_idx < desc->height; h_idx++) {
- memcpy(dst, src, config->pixel_bytes * desc->width);
- src += config->pixel_bytes * desc->pitch;
- dst += config->pixel_bytes * config->rgb_mode.panelWidth;
+ LOG_DBG("Setting FB from %p->%p", (void *) dev_data->active_fb,
+ (void *) dev_data->fb[dev_data->next_idx]);
+ /* Set new active framebuffer */
+ dev_data->active_fb = dev_data->fb[dev_data->next_idx];
}
+
#ifdef CONFIG_HAS_MCUX_CACHE
- DCACHE_CleanByRange((uint32_t) dev_data->fb[write_idx],
- config->fb_bytes);
+ DCACHE_CleanByRange((uint32_t) dev_data->active_fb, config->fb_bytes);
#endif
-#ifdef CONFIG_MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
- ELCDIF_SetNextBufferAddr(config->base,
- (uint32_t) dev_data->fb[write_idx]);
+ /* Queue next framebuffer */
+ ELCDIF_SetNextBufferAddr(config->base, (uint32_t)dev_data->active_fb);
+
+#if CONFIG_MCUX_ELCDIF_FB_NUM != 0
+ /* Update index of active framebuffer */
+ dev_data->next_idx =
+ (dev_data->next_idx + 1) % CONFIG_MCUX_ELCDIF_FB_NUM;
#endif
-
- dev_data->write_idx = write_idx;
-
+ /* Enable frame buffer completion interrupt */
+ ELCDIF_EnableInterrupts(config->base,
+ kELCDIF_CurFrameDoneInterruptEnable);
+ /* Wait for frame send to complete */
+ k_sem_take(&dev_data->sem, K_FOREVER);
return 0;
}
@@ -112,14 +133,14 @@
static void *mcux_elcdif_get_framebuffer(const struct device *dev)
{
-#ifdef CONFIG_MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
+ /*
+ * Direct FB access is not available. If the user wants to set
+ * the framebuffer directly, they must provide a buffer to
+ * `display_write` equal in size to the connected display,
+ * with coordinates [0,0]
+ */
LOG_ERR("Direct framebuffer access not available");
return NULL;
-#else
- struct mcux_elcdif_data *dev_data = dev->data;
-
- return dev_data->fb_ptr;
-#endif
}
static int mcux_elcdif_display_blanking_off(const struct device *dev)
@@ -194,8 +215,14 @@
status = ELCDIF_GetInterruptStatus(config->base);
ELCDIF_ClearInterruptStatus(config->base, status);
-
- k_sem_give(&dev_data->sem);
+ if (config->base->CUR_BUF == ((uint32_t)dev_data->active_fb)) {
+ /* Disable frame completion interrupt, post to
+ * sem to notify that frame send is complete.
+ */
+ ELCDIF_DisableInterrupts(config->base,
+ kELCDIF_CurFrameDoneInterruptEnable);
+ k_sem_give(&dev_data->sem);
+ }
}
static int mcux_elcdif_init(const struct device *dev)
@@ -223,20 +250,19 @@
rgb_mode.pixelFormat = kELCDIF_PixelFormatRGB888;
}
- dev_data->fb[0] = dev_data->fb_ptr;
-#ifdef CONFIG_MCUX_ELCDIF_DOUBLE_FRAMEBUFFER
- dev_data->fb[1] = dev_data->fb_ptr + config->fb_bytes;
-#endif
+ for (int i = 0; i < CONFIG_MCUX_ELCDIF_FB_NUM; i++) {
+ /* Record pointers to each driver framebuffer */
+ dev_data->fb[i] = config->fb_ptr + (config->fb_bytes * i);
+ }
- rgb_mode.bufferAddr = (uint32_t) dev_data->fb_ptr;
+ rgb_mode.bufferAddr = (uint32_t) config->fb_ptr;
+ dev_data->active_fb = config->fb_ptr;
- k_sem_init(&dev_data->sem, 1, 1);
+ k_sem_init(&dev_data->sem, 0, 1);
config->irq_config_func(dev);
ELCDIF_RgbModeInit(config->base, &rgb_mode);
- ELCDIF_EnableInterrupts(config->base,
- kELCDIF_CurFrameDoneInterruptEnable);
ELCDIF_RgbModeStart(config->base);
return 0;
@@ -261,6 +287,10 @@
#define MCUX_ELCDIF_DEVICE_INIT(id) \
PINCTRL_DT_INST_DEFINE(id); \
static void mcux_elcdif_config_func_##id(const struct device *dev); \
+ static uint8_t __aligned(64) frame_buffer_##id[CONFIG_MCUX_ELCDIF_FB_NUM\
+ * DT_INST_PROP(id, width) \
+ * DT_INST_PROP(id, height) \
+ * MCUX_ELCDIF_PIXEL_BYTES(id)]; \
static const struct mcux_elcdif_config mcux_elcdif_config_##id = { \
.base = (LCDIF_Type *) DT_INST_REG_ADDR(id), \
.irq_config_func = mcux_elcdif_config_func_##id, \
@@ -304,14 +334,11 @@
* MCUX_ELCDIF_PIXEL_BYTES(id), \
.pincfg = PINCTRL_DT_INST_DEV_CONFIG_GET(id), \
.backlight_gpio = GPIO_DT_SPEC_INST_GET(id, backlight_gpios), \
- }; \
- static uint8_t __aligned(64) frame_buffer_##id[MCUX_ELCDIF_FB_NUM \
- * DT_INST_PROP(id, width) \
- * DT_INST_PROP(id, height) \
- * MCUX_ELCDIF_PIXEL_BYTES(id)]; \
- static struct mcux_elcdif_data mcux_elcdif_data_##id = { \
.fb_ptr = frame_buffer_##id, \
}; \
+ static struct mcux_elcdif_data mcux_elcdif_data_##id = { \
+ .next_idx = 0, \
+ }; \
DEVICE_DT_INST_DEFINE(id, \
&mcux_elcdif_init, \
NULL, \
