Re: [PATCH v2 3/4] drm/mediatek: Add casting before assign

1. Add casting before assign to avoid the unintentional integer
    overflow or unintended sign extension.
2. Add a int varriable for multiplier calculation instead of calculating
    different types multiplier with dma_addr_t varriable directly.

Signed-off-by: Jason-JH.Lin <redacted>
Fixes: 1a64a7aff8da ("drm/mediatek: Fix cursor plane no update")
---
  drivers/gpu/drm/mediatek/mtk_drm_gem.c   |  2 +-
  drivers/gpu/drm/mediatek/mtk_drm_plane.c | 22 +++++++++++++---------
  2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index a25b28d3ee90..0c7878bc0b37 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c

@@ -121,7 +121,7 @@ int mtk_drm_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
  	int ret;
  
  	args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-	args->size = args->pitch * args->height;
+	args->size = (__u64)args->pitch * args->height;

  
  	mtk_gem = mtk_drm_gem_create(dev, args->size, false);
  	if (IS_ERR(mtk_gem))

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
index 31f9420aff6f..1cd41454d545 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c

@@ -145,6 +145,7 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
  	dma_addr_t addr;
  	dma_addr_t hdr_addr = 0;
  	unsigned int hdr_pitch = 0;
+	int offset;

  
  	gem = fb->obj[0];
  	mtk_gem = to_mtk_gem_obj(gem);

@@ -154,8 +155,10 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
  	modifier = fb->modifier;
  
  	if (modifier == DRM_FORMAT_MOD_LINEAR) {
-		addr += (new_state->src.x1 >> 16) * fb->format->cpp[0];
-		addr += (new_state->src.y1 >> 16) * pitch;
+		offset = (new_state->src.x1 >> 16) * fb->format->cpp[0];
+		addr += offset;
+		offset = (new_state->src.y1 >> 16) * pitch;
+		addr += offset;
  	} else {
  		int width_in_blocks = ALIGN(fb->width, AFBC_DATA_BLOCK_WIDTH)
  				      / AFBC_DATA_BLOCK_WIDTH;

@@ -163,21 +166,22 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
  				       / AFBC_DATA_BLOCK_HEIGHT;
  		int x_offset_in_blocks = (new_state->src.x1 >> 16) / AFBC_DATA_BLOCK_WIDTH;
  		int y_offset_in_blocks = (new_state->src.y1 >> 16) / AFBC_DATA_BLOCK_HEIGHT;
-		int hdr_size;
+		int hdr_size, hdr_offset;
  
  		hdr_pitch = width_in_blocks * AFBC_HEADER_BLOCK_SIZE;
  		pitch = width_in_blocks * AFBC_DATA_BLOCK_WIDTH *
  			AFBC_DATA_BLOCK_HEIGHT * fb->format->cpp[0];
  
  		hdr_size = ALIGN(hdr_pitch * height_in_blocks, AFBC_HEADER_ALIGNMENT);
+		hdr_offset = hdr_pitch * y_offset_in_blocks +
+			AFBC_HEADER_BLOCK_SIZE * x_offset_in_blocks;
+		hdr_addr = addr + hdr_offset;
  
-		hdr_addr = addr + hdr_pitch * y_offset_in_blocks +
-			   AFBC_HEADER_BLOCK_SIZE * x_offset_in_blocks;
  		/* The data plane is offset by 1 additional block. */
-		addr = addr + hdr_size +
-		       pitch * y_offset_in_blocks +
-		       AFBC_DATA_BLOCK_WIDTH * AFBC_DATA_BLOCK_HEIGHT *
-		       fb->format->cpp[0] * (x_offset_in_blocks + 1);
+		offset = pitch * y_offset_in_blocks +
+			 AFBC_DATA_BLOCK_WIDTH * AFBC_DATA_BLOCK_HEIGHT *
+			 fb->format->cpp[0] * (x_offset_in_blocks + 1);
+		addr = addr + hdr_size + offset;
  	}
  
  	mtk_plane_state->pending.enable = true;