Re: [PATCH v2 1/2] drm: Remove plane hsub/vsub alignment requirement for core helpers

[André Almeida]

Hi Carlos,

On 9/26/23 16:15, Carlos Eduardo Gallo Filho wrote:

The drm_format_info_plane_{height,width} functions was implemented using
regular division for the plane size calculation, which cause issues [1][2]
when used on contexts where the dimensions are misaligned with relation
to the subsampling factors. So, replace the regular division by the
DIV_ROUND_UP macro.

This allows these functions to be used in more drivers, making further
work to bring more core presence on them possible.

[1] 
http://patchwork.freedesktop.org/patch/msgid/20170321181218.10042-3-ville.syrj...@linux.intel.com
[2] 
https://patchwork.freedesktop.org/patch/msgid/20211026225105.2783797-2-imre.d...@intel.com

Prefer to use lore:

https://lore.kernel.org/dri-devel/20170321181218.10042-3-ville.syrj...@linux.intel.com/

https://lore.kernel.org/intel-gfx/20211026225105.2783797-2-imre.d...@intel.com/


Other than that,

Reviewed-by: André Almeida <andrealm...@igalia.com>

Signed-off-by: Carlos Eduardo Gallo Filho <gcar...@disroot.org>
---
  include/drm/drm_fourcc.h | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 532ae78ca747..ccf91daa4307 100644
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -22,6 +22,7 @@
  #ifndef __DRM_FOURCC_H__
  #define __DRM_FOURCC_H__

+#include <linux/math.h>

  #include <linux/types.h>
  #include <uapi/drm/drm_fourcc.h>

@@ -279,7 +280,7 @@ int drm_format_info_plane_width(const struct drm_format_info *info, int width,

        if (plane == 0)
                return width;

- return width / info->hsub;

+       return DIV_ROUND_UP(width, info->hsub);
  }

/**

@@ -301,7 +302,7 @@ int drm_format_info_plane_height(const struct 
drm_format_info *info, int height,
        if (plane == 0)
                return height;

- return height / info->vsub;

+       return DIV_ROUND_UP(height, info->vsub);
  }

const struct drm_format_info *__drm_format_info(u32 format);