[PATCH] media: i2c: maxim-serdes: reduce max_des_update_streams() stack usage

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

The function can break the stack frame warning limit in
some configurations:

drivers/media/i2c/maxim-serdes/max_des.c: In function 'max_des_update_streams.isra':
drivers/media/i2c/maxim-serdes/max_des.c:2550:1: error: the frame size of 1648 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]
 2550 | }
      | ^

This is a simple large structure on the stack that shouldn't be
there. Move both instances into a dynamically allocated structure
instead.

Fixes: 22923bc4512c ("media: i2c: add Maxim GMSL2/3 deserializer framework")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/media/i2c/maxim-serdes/max_des.c | 28 ++++++++++++++----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/media/i2c/maxim-serdes/max_des.c b/drivers/media/i2c/maxim-serdes/max_des.c
index 6b4ffd0e2415..4347ca24b5a1 100644
--- a/drivers/media/i2c/maxim-serdes/max_des.c
+++ b/drivers/media/i2c/maxim-serdes/max_des.c
@@ -2164,7 +2164,7 @@ static int max_des_get_frame_desc_state(struct v4l2_subdev *sd,
 					struct v4l2_mbus_frame_desc *fd,
 					unsigned int pad)
 {
-	struct max_des_remap_context context = { 0 };
+	struct max_des_remap_context __free(kfree) *context = kzalloc_obj(*context);
 	struct max_des_priv *priv = sd_to_priv(sd);
 	struct v4l2_subdev_route *route;
 	int ret;
@@ -2172,7 +2172,10 @@ static int max_des_get_frame_desc_state(struct v4l2_subdev *sd,
 	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_CSI2;
 	fd->num_entries = 0;
 
-	ret = max_des_populate_remap_context(priv, &context, state);
+	if (!context)
+		return -ENOMEM;
+
+	ret = max_des_populate_remap_context(priv, context, state);
 	if (ret)
 		return ret;
 
@@ -2187,7 +2190,7 @@ static int max_des_get_frame_desc_state(struct v4l2_subdev *sd,
 		if (ret)
 			return ret;
 
-		ret = max_des_get_src_dst_vc_id(&context, hw.pipe->index, hw.phy->index,
+		ret = max_des_get_src_dst_vc_id(context, hw.pipe->index, hw.phy->index,
 						hw.entry.bus.csi2.vc, &dst_vc_id);
 		if (ret)
 			return ret;
@@ -2450,18 +2453,21 @@ static int max_des_update_streams(struct v4l2_subdev *sd,
 				  u32 pad, u64 updated_streams_mask, bool enable)
 {
 	struct max_des_priv *priv = v4l2_get_subdevdata(sd);
-	struct max_des_remap_context context = { 0 };
+	struct max_des_remap_context *context __free(kfree) = kzalloc_obj(*context);
 	struct max_des_mode_context mode_context = { 0 };
 	struct max_des *des = priv->des;
 	unsigned int num_pads = max_des_num_pads(des);
 	u64 *streams_masks;
 	int ret;
 
-	ret = max_des_populate_remap_context(priv, &context, state);
+	if (!context)
+		return -ENOMEM;
+
+	ret = max_des_populate_remap_context(priv, context, state);
 	if (ret)
 		return ret;
 
-	ret = max_des_populate_mode_context(priv, &mode_context, state, context.mode);
+	ret = max_des_populate_mode_context(priv, &mode_context, state, context->mode);
 	if (ret)
 		return ret;
 
@@ -2471,11 +2477,11 @@ static int max_des_update_streams(struct v4l2_subdev *sd,
 	if (ret)
 		return ret;
 
-	ret = max_des_set_pipes_phy(priv, &context);
+	ret = max_des_set_pipes_phy(priv, context);
 	if (ret)
 		goto err_free_streams_masks;
 
-	ret = max_des_set_tunnel(priv, &context);
+	ret = max_des_set_tunnel(priv, context);
 	if (ret)
 		goto err_free_streams_masks;
 
@@ -2483,7 +2489,7 @@ static int max_des_update_streams(struct v4l2_subdev *sd,
 	if (ret)
 		goto err_free_streams_masks;
 
-	ret = max_des_set_vc_remaps(priv, &context, state, streams_masks);
+	ret = max_des_set_vc_remaps(priv, context, state, streams_masks);
 	if (ret)
 		goto err_free_streams_masks;
 
@@ -2502,7 +2508,7 @@ static int max_des_update_streams(struct v4l2_subdev *sd,
 	if (ret)
 		goto err_revert_streams_disable;
 
-	ret = max_des_update_links(priv, &context, state, streams_masks);
+	ret = max_des_update_links(priv, context, state, streams_masks);
 	if (ret)
 		goto err_revert_active_disable;
 
@@ -2533,7 +2539,7 @@ static int max_des_update_streams(struct v4l2_subdev *sd,
 	max_des_update_tpg(priv, state, priv->streams_masks);
 
 err_revert_links_update:
-	max_des_update_links(priv, &context, state, priv->streams_masks);
+	max_des_update_links(priv, context, state, priv->streams_masks);
 
 err_revert_active_disable:
 	max_des_update_active(priv, priv->streams_masks, true);
-- 
2.53.0