drm/vc4: bo: Split out Dumb buffers fixup

The vc4_bo_dumb_create() both fixes up the allocation arguments to match
the hardware constraints and actually performs the allocation.

Since we're going to introduce a new function that uses a different
allocator, let's split the arguments fixup to a separate function we
will be able to reuse.
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220610115149.964394-5-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_bo.c

@@ -475,15 +475,12 @@ int vc4_bo_dumb_create(struct drm_file *file_priv,
 		       struct drm_device *dev,
 		       struct drm_mode_create_dumb *args)
 {
-	int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 	struct vc4_bo *bo = NULL;
 	int ret;
 
-	if (args->pitch < min_pitch)
-		args->pitch = min_pitch;
-
-	if (args->size < args->pitch * args->height)
-		args->size = args->pitch * args->height;
+	ret = vc4_dumb_fixup_args(args);
+	if (ret)
+		return ret;
 
 	bo = vc4_bo_create(dev, args->size, false, VC4_BO_TYPE_DUMB);
 	if (IS_ERR(bo))

drivers/gpu/drm/vc4/vc4_drv.c

@@ -63,6 +63,19 @@ void __iomem *vc4_ioremap_regs(struct platform_device *pdev, int index)
 	return map;
 }
 
+int vc4_dumb_fixup_args(struct drm_mode_create_dumb *args)
+{
+	int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
+
+	if (args->pitch < min_pitch)
+		args->pitch = min_pitch;
+
+	if (args->size < args->pitch * args->height)
+		args->size = args->pitch * args->height;
+
+	return 0;
+}
+
 static int vc4_get_param_ioctl(struct drm_device *dev, void *data,
 			       struct drm_file *file_priv)
 {

drivers/gpu/drm/vc4/vc4_drv.h

@@ -885,6 +885,7 @@ static inline void vc4_debugfs_add_regset32(struct drm_device *drm,
 
 /* vc4_drv.c */
 void __iomem *vc4_ioremap_regs(struct platform_device *dev, int index);
+int vc4_dumb_fixup_args(struct drm_mode_create_dumb *args);
 
 /* vc4_dpi.c */
 extern struct platform_driver vc4_dpi_driver;