Fix camera-vflip/hflip support on arm32v7

This adds `buffer_list_alloc_buffers` and `buffer_list_free_buffers`
to delay buffers allocation for `libcamera`.

Doing this allows to setup RAW stream afterwards.

device/buffer_list.c

@@ -4,31 +4,19 @@
 #include "util/opts/log.h"
 #include "util/opts/fourcc.h"
 
-buffer_list_t *buffer_list_open(const char *name, int index, struct device_s *dev, const char *path, buffer_format_t fmt, bool do_capture, bool do_mmap)
+static int buffer_list_alloc_buffers2(buffer_list_t *buf_list, int got_bufs)
 {
-  buffer_list_t *buf_list = calloc(1, sizeof(buffer_list_t));
-
-  buf_list->dev = dev;
-  buf_list->name = strdup(name);
-  if (path) {
-    buf_list->path = strdup(path);
-  }
-  buf_list->do_capture = do_capture;
-  buf_list->do_mmap = do_mmap;
-  buf_list->fmt = fmt;
-  buf_list->index = index;
-
-  int got_bufs = dev->hw->buffer_list_open(buf_list);
-  if (got_bufs < 0) {
-    goto error;
+  if (buf_list->bufs || got_bufs <= 0) {
+    return -1;
   }
 
 	LOG_INFO(
     buf_list,
-    "Using: %ux%u/%s, bytesperline=%d, sizeimage=%.1fMiB",
+    "Using: %ux%u/%s, buffers=%d, bytesperline=%d, sizeimage=%.1fMiB",
     buf_list->fmt.width,
     buf_list->fmt.height,
     fourcc_to_string(buf_list->fmt.format).buf,
+    got_bufs,
     buf_list->fmt.bytesperline,
     buf_list->fmt.sizeimage / 1024.0f / 1024.0f
   );
@@ -56,6 +44,35 @@ buffer_list_t *buffer_list_open(const char *name, int index, struct device_s *de
   }
 
   LOG_INFO(buf_list, "Opened %u buffers. Memory used: %.1f MiB", buf_list->nbufs, mem_used / 1024.0f / 1024.0f);
+  return 0;
+
+error:
+  buffer_list_free_buffers(buf_list);
+  return -1;
+}
+
+buffer_list_t *buffer_list_open(const char *name, int index, struct device_s *dev, const char *path, buffer_format_t fmt, bool do_capture, bool do_mmap)
+{
+  buffer_list_t *buf_list = calloc(1, sizeof(buffer_list_t));
+
+  buf_list->dev = dev;
+  buf_list->name = strdup(name);
+  if (path) {
+    buf_list->path = strdup(path);
+  }
+  buf_list->do_capture = do_capture;
+  buf_list->do_mmap = do_mmap;
+  buf_list->fmt = fmt;
+  buf_list->index = index;
+
+  int err = dev->hw->buffer_list_open(buf_list);
+  if (err > 0) {
+    err = buffer_list_alloc_buffers2(buf_list, err);
+  }
+
+  if (err < 0) {
+    goto error;
+  }
 
   return buf_list;
 
@@ -64,20 +81,48 @@ error:
   return NULL;
 }
 
+int buffer_list_alloc_buffers(buffer_list_t *buf_list)
+{
+  if (buf_list->bufs) {
+    return 0;
+  }
+  if (!buf_list->dev->hw->buffer_list_alloc_buffers) {
+    return -1;
+  }
+
+  int got_bufs = buf_list->dev->hw->buffer_list_alloc_buffers(buf_list);
+  if (got_bufs < 0) {
+    return -1;
+  }
+
+  return buffer_list_alloc_buffers2(buf_list, got_bufs);
+}
+
+void buffer_list_free_buffers(buffer_list_t *buf_list)
+{
+  if (!buf_list->bufs) {
+    return;
+  }
+
+  for (int i = 0; i < buf_list->nbufs; i++) {
+    buffer_close(buf_list->bufs[i]);
+  }
+  free(buf_list->bufs);
+  buf_list->bufs = NULL;
+  buf_list->nbufs = 0;
+
+  if (buf_list->dev->hw->buffer_list_free_buffers) {
+    buf_list->dev->hw->buffer_list_free_buffers(buf_list);
+  }
+}
+
 void buffer_list_close(buffer_list_t *buf_list)
 {
   if (!buf_list) {
     return;
   }
 
-  if (buf_list->bufs) {
-    for (int i = 0; i < buf_list->nbufs; i++) {
-      buffer_close(buf_list->bufs[i]);
-    }
-    free(buf_list->bufs);
-    buf_list->bufs = NULL;
-    buf_list->nbufs = 0;
-  }
+  buffer_list_free_buffers(buf_list);
 
   buf_list->dev->hw->buffer_list_close(buf_list);
   free(buf_list->name);