fix(esp_lvgl_port): support CONFIG_LCD_RGB_ISR_IRAM_SAFE for RGB panels (BSP-787)

[matiasgibbons]

Problem

On ESP32-S3 with RGB LCD panels in bounce buffer mode, enabling
CONFIG_LCD_RGB_ISR_IRAM_SAFE=y causes a LoadProhibited crash at boot:

The root cause is that lvgl_port_flush_rgb_vsync_ready_callback() calls
lv_display_get_driver_data(), which resides in flash. When SPI flash
operations disable the cache, the ISR tries to execute from flash → crash.

Without CONFIG_LCD_RGB_ISR_IRAM_SAFE, the callback works but DMA underruns
can occur during flash operations, causing visible white horizontal lines on
the display (tearing artifacts).

Solution

When CONFIG_LCD_RGB_ISR_IRAM_SAFE is enabled:

1. Mark the callback with IRAM_ATTR
2. Pass disp_ctx (already in SRAM) directly as user_ctx instead of
   disp_drv (lv_display_t*), avoiding the need to call
   lv_display_get_driver_data() from ISR context
3. Access disp_ctx->trans_sem directly (xSemaphoreGiveFromISR is always in IRAM)

When CONFIG_LCD_RGB_ISR_IRAM_SAFE is not set, behavior is 100% unchanged.

Testing

• ESP32-S3 + ST7277 RGB 800×480 panel, bounce buffer mode, PSRAM canvas
• Verified no crash with CONFIG_LCD_RGB_ISR_IRAM_SAFE=y
• Verified white line artifacts eliminated during SPI flash operations
• Verified backward compatibility without the config option

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Note

Medium Risk
Touches ISR callback wiring and memory placement for display contexts, which can impact stability on constrained targets if allocation/callback assumptions differ across IDF versions. Changes are gated by CONFIG_LCD_RGB_ISR_IRAM_SAFE and otherwise preserve existing behavior.

Overview
Fixes ESP32-S3 RGB panel ISR crashes/tearing when CONFIG_LCD_RGB_ISR_IRAM_SAFE is enabled by making the RGB vsync/bounce-buffer callback IRAM-safe and avoiding flash-resident LVGL access.

When the config is on, RGB panel event callbacks now receive disp_ctx directly as user_ctx, lvgl_port_flush_rgb_vsync_ready_callback() is built with IRAM_ATTR and no longer calls lv_display_get_driver_data() from ISR context, and the display context allocation is forced into internal RAM via heap_caps_malloc(..., MALLOC_CAP_INTERNAL); behavior is unchanged when the config is off.

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Pull request overview

This PR updates the ESP LVGL port’s RGB panel VSYNC/bounce-buffer callback path to support CONFIG_LCD_RGB_ISR_IRAM_SAFE on ESP32-S3 by ensuring the callback can run safely with cache disabled (e.g., during SPI flash operations).

Changes:

• Adds an IRAM-safe variant of lvgl_port_flush_rgb_vsync_ready_callback() guarded by CONFIG_LCD_RGB_ISR_IRAM_SAFE.
• Passes disp_ctx as the RGB panel callback user_ctx when IRAM-safe mode is enabled to avoid calling lv_display_get_driver_data() from ISR context.
• Keeps the existing behavior unchanged when CONFIG_LCD_RGB_ISR_IRAM_SAFE is disabled.

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