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rgb_lcd: support restart dma transmission manually

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When doing Flash operations (e.g. OTA), LCD's DMA bandwidth will be not
sufficient, causing the desync between the LCD controller and DMA.

Added a restart function to help the user to make them sync again.
This commit is contained in:
morris
2022-09-22 17:52:52 +08:00
parent 052dc64616
commit 05092e2f82
5 changed files with 92 additions and 22 deletions
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56
components/esp_lcd/src/esp_lcd_rgb_panel.c
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@@ -115,6 +115,7 @@ struct esp_rgb_panel_t {
uint32_t no_fb: 1; // No frame buffer allocated in the driver
uint32_t fb_in_psram: 1; // Whether the frame buffer is in PSRAM
uint32_t need_update_pclk: 1; // Whether to update the PCLK before start a new transaction
uint32_t need_restart: 1; // Whether to restart the LCD controller and the DMA
uint32_t bb_invalidate_cache: 1; // Whether to do cache invalidation in bounce buffer mode
} flags;
dma_descriptor_t *dma_links[2]; // fbs[0] <-> dma_links[0], fbs[1] <-> dma_links[1]
@@ -362,6 +363,19 @@ esp_err_t esp_lcd_rgb_panel_set_pclk(esp_lcd_panel_handle_t panel, uint32_t freq
return ESP_OK;
}
esp_err_t esp_lcd_rgb_panel_restart(esp_lcd_panel_handle_t panel)
{
ESP_RETURN_ON_FALSE(panel, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
esp_rgb_panel_t *rgb_panel = __containerof(panel, esp_rgb_panel_t, base);
ESP_RETURN_ON_FALSE(rgb_panel->flags.stream_mode, ESP_ERR_INVALID_STATE, TAG, "not in stream mode");
// the underlying restart job will be done in the `LCD_LL_EVENT_VSYNC_END` event handler
portENTER_CRITICAL(&rgb_panel->spinlock);
rgb_panel->flags.need_restart = true;
portEXIT_CRITICAL(&rgb_panel->spinlock);
return ESP_OK;
}
esp_err_t esp_lcd_rgb_panel_get_frame_buffer(esp_lcd_panel_handle_t panel, uint32_t fb_num, void **fb0, ...)
{
ESP_RETURN_ON_FALSE(panel, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
@@ -996,16 +1010,15 @@ static esp_err_t lcd_rgb_panel_create_trans_link(esp_rgb_panel_t *panel)
}
}
#if CONFIG_LCD_RGB_RESTART_IN_VSYNC
// On restart, the data sent to the LCD peripheral needs to start LCD_FIFO_PRESERVE_SIZE_PX pixels after the FB start
// so we use a dedicated DMA node to restart the DMA transaction
// see also `lcd_rgb_panel_try_restart_transmission`
memcpy(&panel->dma_restart_node, &panel->dma_nodes[0], sizeof(panel->dma_restart_node));
int restart_skip_bytes = LCD_FIFO_PRESERVE_SIZE_PX * sizeof(uint16_t);
uint8_t *p = (uint8_t *)panel->dma_restart_node.buffer;
panel->dma_restart_node.buffer = &p[restart_skip_bytes];
panel->dma_restart_node.dw0.length -= restart_skip_bytes;
panel->dma_restart_node.dw0.size -= restart_skip_bytes;
#endif
// alloc DMA channel and connect to LCD peripheral
gdma_channel_alloc_config_t dma_chan_config = {
@@ -1030,9 +1043,31 @@ static esp_err_t lcd_rgb_panel_create_trans_link(esp_rgb_panel_t *panel)
return ESP_OK;
}
#if CONFIG_LCD_RGB_RESTART_IN_VSYNC
static IRAM_ATTR void lcd_rgb_panel_restart_transmission_in_isr(esp_rgb_panel_t *panel)
// reset the GDMA channel every VBlank to stop permanent desyncs from happening.
// Note that this fix can lead to single-frame desyncs itself, as in: if this interrupt
// is late enough, the display will shift as the LCD controller already read out the
// first data bytes, and resetting DMA will re-send those. However, the single-frame
// desync this leads to is preferable to the permanent desync that could otherwise
// happen. It's also not super-likely as this interrupt has the entirety of the VBlank
// time to reset DMA.
static IRAM_ATTR void lcd_rgb_panel_try_restart_transmission(esp_rgb_panel_t *panel)
{
bool do_restart = false;
#if CONFIG_LCD_RGB_RESTART_IN_VSYNC
do_restart = true;
#else
portENTER_CRITICAL_ISR(&panel->spinlock);
if (panel->flags.need_restart) {
panel->flags.need_restart = false;
do_restart = true;
}
portEXIT_CRITICAL_ISR(&panel->spinlock);
#endif // CONFIG_LCD_RGB_RESTART_IN_VSYNC
if (!do_restart) {
return;
}
if (panel->bb_size) {
// Catch de-synced frame buffer and reset if needed.
if (panel->bounce_pos_px > panel->bb_size) {
@@ -1055,7 +1090,6 @@ static IRAM_ATTR void lcd_rgb_panel_restart_transmission_in_isr(esp_rgb_panel_t
}
}
}
#endif
static void lcd_rgb_panel_start_transmission(esp_rgb_panel_t *rgb_panel)
{
@@ -1109,16 +1143,8 @@ IRAM_ATTR static void lcd_default_isr_handler(void *args)
lcd_rgb_panel_try_update_pclk(rgb_panel);
if (rgb_panel->flags.stream_mode) {
#if CONFIG_LCD_RGB_RESTART_IN_VSYNC
// reset the GDMA channel every VBlank to stop permanent desyncs from happening.
// Note that this fix can lead to single-frame desyncs itself, as in: if this interrupt
// is late enough, the display will shift as the LCD controller already read out the
// first data bytes, and resetting DMA will re-send those. However, the single-frame
// desync this leads to is preferable to the permanent desync that could otherwise
// happen. It's also not super-likely as this interrupt has the entirety of the VBlank
// time to reset DMA.
lcd_rgb_panel_restart_transmission_in_isr(rgb_panel);
#endif
// check whether to restart the transmission
lcd_rgb_panel_try_restart_transmission(rgb_panel);
}
}