feat(dma2d): add support for ARGB1555 color on top of RGB565 format (#7555)

Signed-off-by: Felipe Neves <felipe@lvgl.io>

docs/details/integration/chip/stm32.rst

@@ -292,4 +292,8 @@ If ``LV_USE_DRAW_DMA2D_INTERRUPT`` is enabled then you are required to call
 :cpp:expr:`lv_draw_dma2d_transfer_complete_interrupt_handler` whenever the DMA2D
 "transfer complete" global interrupt is received.
 
+DMA2D also makes possible to mix layers that have color format on
+:c:macro:`LV_COLOR_FORMAT_ARGB1555` on top of :c:macro:`LV_COLOR_FORMAT_RGB565`
+layers.
+
 If your STM device has a NeoChrom GPU, you can use the :ref:`Nema GFX renderer <nema_gfx>` instead.

docs/details/integration/driver/display/st_ltdc.rst

@@ -103,6 +103,10 @@ partial buffers in parallel with other LVGL tasks, whether or not OS is
 enabled. If the display is not partial, then there is no need to enable this
 option.
 
+Additionally it is possible to mix layers that have color format on
+:c:macro:`LV_COLOR_FORMAT_ARGB1555` on top of :c:macro:`LV_COLOR_FORMAT_RGB565`
+layers using the DMA2D.
+
 It must not be enabled at the same time as :c:macro:`LV_USE_DRAW_DMA2D`.
 See the :ref:`DMA2D support <dma2d>`.
 

src/draw/dma2d/lv_draw_dma2d.c

@@ -131,6 +131,8 @@ lv_draw_dma2d_output_cf_t lv_draw_dma2d_cf_to_dma2d_output_cf(lv_color_format_t
             return LV_DRAW_DMA2D_OUTPUT_CF_RGB888;
         case LV_COLOR_FORMAT_RGB565:
             return LV_DRAW_DMA2D_OUTPUT_CF_RGB565;
+        case LV_COLOR_FORMAT_ARGB1555:
+            return LV_DRAW_DMA2D_OUTPUT_CF_ARGB1555;
         default:
             LV_ASSERT_MSG(false, "unsupported output color format");
     }
@@ -310,7 +312,8 @@ static int32_t evaluate_cb(lv_draw_unit_t * draw_unit, lv_draw_task_t * task)
                      && (dsc->header.cf == LV_COLOR_FORMAT_ARGB8888
                          || dsc->header.cf == LV_COLOR_FORMAT_XRGB8888
                          || dsc->header.cf == LV_COLOR_FORMAT_RGB888
-                         || dsc->header.cf == LV_COLOR_FORMAT_RGB565)
+                         || dsc->header.cf == LV_COLOR_FORMAT_RGB565
+                         || dsc->header.cf == LV_COLOR_FORMAT_ARGB1555)
                      && (dsc->base.layer->color_format == LV_COLOR_FORMAT_ARGB8888
                          || dsc->base.layer->color_format == LV_COLOR_FORMAT_XRGB8888
                          || dsc->base.layer->color_format == LV_COLOR_FORMAT_RGB888