drivers: video: video_stm32_dcmi: Use shared multi-heap if enabled.

The stm32 video driver currently allocates a static pool in SRAM which:
a) Does not respect the alignment specified in `CONFIG_VIDEO_BUFFER_POOL_ALIGN`.
b) Overflows the SRAM if multi-heap is enabled and a bigger buffer size is used.

This patch allocates an aligned DCMI buffer from the shared multi-heap pool
(if enabled), or from the static pool if not, similar to how it's done in
`video_common.c`.

Signed-off-by: Ibrahim Abdalkader <[email protected]>

drivers/video/video_stm32_dcmi.c

@@ -22,7 +22,17 @@
 
 LOG_MODULE_REGISTER(video_stm32_dcmi, CONFIG_VIDEO_LOG_LEVEL);
 
+#if defined(CONFIG_VIDEO_BUFFER_USE_SHARED_MULTI_HEAP)
+#include <zephyr/multi_heap/shared_multi_heap.h>
+#define VIDEO_STM32_HEAP_ALLOC(align, size, timeout)                                              \
+	shared_multi_heap_aligned_alloc(CONFIG_VIDEO_BUFFER_SMH_ATTRIBUTE, align, size)
+#define VIDEO_STM32_HEAP_FREE(block) shared_multi_heap_free(block)
+#else
 K_HEAP_DEFINE(video_stm32_buffer_pool, CONFIG_VIDEO_BUFFER_POOL_SZ_MAX);
+#define VIDEO_STM32_HEAP_ALLOC(align, size, timeout)                                              \
+	k_heap_aligned_alloc(&video_stm32_buffer_pool, align, size, timeout);
+#define VIDEO_STM32_HEAP_FREE(block) k_heap_free(&video_stm32_buffer_pool, block)
+#endif
 
 typedef void (*irq_config_func_t)(const struct device *dev);
 
@@ -246,7 +256,7 @@ static int video_stm32_dcmi_stream_start(const struct device *dev)
 	const struct video_stm32_dcmi_config *config = dev->config;
 	size_t buffer_size = data->pitch * data->height;
 
-	data->buffer = k_heap_alloc(&video_stm32_buffer_pool, buffer_size, K_NO_WAIT);
+	data->buffer = VIDEO_STM32_HEAP_ALLOC(CONFIG_VIDEO_BUFFER_POOL_ALIGN, buffer_size, K_NO_WAIT);
 	if (data->buffer == NULL) {
 		LOG_ERR("Failed to allocate DCMI buffer for image. Size %d bytes", buffer_size);
 		return -ENOMEM;
@@ -277,7 +287,7 @@ static int video_stm32_dcmi_stream_stop(const struct device *dev)
 	}
 
 	/* Release the buffer allocated in stream_start */
-	k_heap_free(&video_stm32_buffer_pool, data->buffer);
+	VIDEO_STM32_HEAP_FREE(data->buffer);
 
 	err = HAL_DCMI_Stop(&data->hdcmi);
 	if (err != HAL_OK) {