Update changelog.txt

changelog.txt

@@ -8,7 +8,13 @@ FIX:		Fixed GWIN console widget scroll
 FIX:		A warning and adjusted is made if GDISP_IMAGE_BMP_BLIT_BUFFER_SIZE is less than 40 bytes.
 FIX:        Prevent compiler warnings on duplicate const specifiers.
 FEATURE:	Added support for ChibiOS 6.x kernel.
-CHANGE:		Refactor STM32LTDC driver to outsource hardware specifics such as clock setup to the board file.
+CHANGE:		STM32LTDC driver: Refactor to outsource clock setup for LTDC & DMA2D peripherals to the board file.
+CHANGE:     STM32LTDC driver: Remove obsolete LTDC_NO_CLOCK_INIT macro as this clock setup is now outsourced to the board file.
+CHANGE:     STM32LTDC driver: Automatically enable DMA cache flushing on STM32H7 platforms.
+CHANGE:     STM32LTDC driver: Rename ALLOW_2ND_LAYER to STM32LTDC_USE_LAYER2.
+CHANGE:     STM32LTDC driver: Rename LTDC_DMA_CACHE_FLUSH to STM32LTDC_DMA_CACHE_FLUSH.
+CHANGE:     STM32LTDC driver: Rename GDISP_LTDC_USE_RGB565 to STM32LTDC_USE_RGB565.
+FEATURE:    STM32LTDC driver: Support double buffering. This introduces STM32LTDC_USE_DOUBLEBUFFERING.
 
 
 *** Release 2.9 ***

drivers/gdisp/STM32LTDC/readme.md

@@ -25,7 +25,9 @@ Configuration options available in `gfxconf.h`:
 | `STM32LTDC_USE_RGB565` | `GFXOFF` | Whether to use RGB565 instead of RGB888. |
 
 # 2nd layer
-To use the 2nd LTDC layer, set `STM32LTDC_USE_LAYER2` to `GFXON` in `gfxconf.h`.
+To use the 2nd LTDC layer:
+  - set `STM32LTDC_USE_LAYER2` to `GFXON` in `gfxconf.h`.
+  - set `GDISP_TOTAL_DISPLAYS` to `2` in `gfxconf.h`.
 
 The 2nd layer is exposed as a separate display. Use `gdispGetDisplay()` to retrieve the individual layers.
 
@@ -34,7 +36,9 @@ For more information, see:
   - https://wiki.ugfx.io/index.php/Multiple_displays#Access_the_displays
 
 # Double buffering
-Double buffering can be enabled by setting `STM32LTDC_USE_DOUBLEBUFFERING` to `GFXON`.
+To use double buffering:
+  - set `STM32LTDC_USE_DOUBLEBUFFERING` to `GFXON` in `gfxconf.h`.
+  - set `GDISP_TOTAL_DISPLAYS` to `2` in `gfxconf.h`.
 
 When double buffering is enabled, the 2nd LTDC layer cannot be used. While this limitation is easy to remove from a software perspective, there is little benefit in doing so. Double buffering requires, as the name implies, twice the memory. If the 2nd layer would be used together with double buffering strategy, a total of four full framebuffers would be required. Years of real-world experience shows that there's practically never enough memory bandwidth available to do this.