Re: [PATCH v3 3/4] drm/mediatek: Add casting before assign

Hi Alexandre,

Thanks for the reviews.

On Wed, 2023-06-21 at 14:34 +0200, Alexandre Mergnat wrote:

 	 
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On 21/06/2023 12:22, Jason-JH.Lin wrote:

quoted

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

quoted

    different types multiplier with dma_addr_t varriable directly.

Fixes: 1a64a7aff8da ("drm/mediatek: Fix cursor plane no update")
Signed-off-by: Jason-JH.Lin <redacted>
---
  drivers/gpu/drm/mediatek/mtk_drm_gem.c   |  3 ++-
  drivers/gpu/drm/mediatek/mtk_drm_plane.c | 22 +++++++++++++----

-----

quoted

  2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c

b/drivers/gpu/drm/mediatek/mtk_drm_gem.c

quoted

index a25b28d3ee90..da087d74612d 100644

--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c

@@ -121,7 +121,8 @@ int mtk_drm_gem_dumb_create(struct drm_file

*file_priv, struct drm_device *dev,

quoted

  int ret;
  
  args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
-args->size = args->pitch * args->height;
+args->size = args->pitch;
+args->size *= 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

quoted

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,

quoted

  dma_addr_t addr;
  dma_addr_t hdr_addr = 0;
  unsigned int hdr_pitch = 0;
+int offset;

I agree with Angelo, please set offset as unsigned.

I think offset should be unsigned, but since src.x1 and src.y1 are
'int'. That means 'unsigned int' offset will be very big when src.x1 or
src.y1 is negative.
So I just use 'int' for offset here.

Regards,
Jason-JH.Lin

quoted

  
  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,

quoted

  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;

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