media: rkvdec: vp9: Fix probs struct alignment

[PATCH] media: rkvdec: vp9: Fix probs struct alignment

Posted by Detlev Casanova 1 day, 10 hours ago

When building for arm 32 bits, the struct alignment changes and the compiler
adds 3 padding bits to the anonymous mv struct in
rkvdec_vp9_inter_frame_probs.

Therefore, the BUILD_BUG_ON used to check that the struct size is aligned
to 128 bits (hardware requirement) fails.

As that mv struct is at the end of the global rkvdec_vp9_probs struct
and is followed by 11 padding bits, the 3 padding bits can be explicitely
set in the mv struct and removed from the 11 following it.

This makes sure that the mv struct is 32 bits aligned.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512110229.R6YCf1Le-lkp@intel.com/
Fixes: d968e50b5c26 ("media: rkvdec: Unstage the driver")
Suggested-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
---
 drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
index b4bf01e839ef..23c733ca2e8e 100644
--- a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
+++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
@@ -66,6 +66,8 @@ struct rkvdec_vp9_inter_frame_probs {
 		u8 fr[2][3];
 		u8 class0_hp[2];
 		u8 hp[2];
+		/* 32 bit alignment */
+		u8 padding6[3];
 	} mv;
 };
 
@@ -85,7 +87,7 @@ struct rkvdec_vp9_probs {
 		struct rkvdec_vp9_intra_only_frame_probs intra_only;
 	};
 	/* 128 bit alignment */
-	u8 padding1[11];
+	u8 padding1[8];
 };
 
 /* Data structure describing auxiliary buffer format. */
-- 
2.52.0

Re: [PATCH] media: rkvdec: vp9: Fix probs struct alignment

Posted by Detlev Casanova 1 day, 7 hours ago

Hi all,

Sorry, I need to rewrite the commit message with some s/bit/byte...

Will do a v2 soon.

Regards,

Detlev.

On 12/12/25 11:01, Detlev Casanova wrote:
> When building for arm 32 bits, the struct alignment changes and the compiler
> adds 3 padding bits to the anonymous mv struct in
> rkvdec_vp9_inter_frame_probs.
>
> Therefore, the BUILD_BUG_ON used to check that the struct size is aligned
> to 128 bits (hardware requirement) fails.
>
> As that mv struct is at the end of the global rkvdec_vp9_probs struct
> and is followed by 11 padding bits, the 3 padding bits can be explicitely
> set in the mv struct and removed from the 11 following it.
>
> This makes sure that the mv struct is 32 bits aligned.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512110229.R6YCf1Le-lkp@intel.com/
> Fixes: d968e50b5c26 ("media: rkvdec: Unstage the driver")
> Suggested-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
> ---
>   drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> index b4bf01e839ef..23c733ca2e8e 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> @@ -66,6 +66,8 @@ struct rkvdec_vp9_inter_frame_probs {
>   		u8 fr[2][3];
>   		u8 class0_hp[2];
>   		u8 hp[2];
> +		/* 32 bit alignment */
> +		u8 padding6[3];
>   	} mv;
>   };
>   
> @@ -85,7 +87,7 @@ struct rkvdec_vp9_probs {
>   		struct rkvdec_vp9_intra_only_frame_probs intra_only;
>   	};
>   	/* 128 bit alignment */
> -	u8 padding1[11];
> +	u8 padding1[8];
>   };
>   
>   /* Data structure describing auxiliary buffer format. */

Re: [PATCH] media: rkvdec: vp9: Fix probs struct alignment

Posted by Nicolas Dufresne 1 day, 7 hours ago

Hi,

Le vendredi 12 décembre 2025 à 11:01 -0500, Detlev Casanova a écrit :
> When building for arm 32 bits, the struct alignment changes and the compiler

Reported by checkpatch [0], this needs a reflow, it exceeds 75 chars.

> adds 3 padding bits to the anonymous mv struct in
> rkvdec_vp9_inter_frame_probs.
> 
> Therefore, the BUILD_BUG_ON used to check that the struct size is aligned
> to 128 bits (hardware requirement) fails.
> 
> As that mv struct is at the end of the global rkvdec_vp9_probs struct
> and is followed by 11 padding bits, the 3 padding bits can be explicitely

Also from checkpatch:

explicitely -> explicitly


> set in the mv struct and removed from the 11 following it.
> 
> This makes sure that the mv struct is 32 bits aligned.

Unless someone request a change, I will be able to apply these fixes while
picking it up.

cheers,
Nicolas


[0]https://linux-media.pages.freedesktop.org/-/users/patchwork/-/jobs/89677987/artifacts/junit/0001-media-rkvdec-vp9-Fix-probs-struct-alignment.patch%20checkpatch.err.txt

> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512110229.R6YCf1Le-lkp@intel.com/
> Fixes: d968e50b5c26 ("media: rkvdec: Unstage the driver")
> Suggested-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
> ---
>  drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> index b4bf01e839ef..23c733ca2e8e 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> @@ -66,6 +66,8 @@ struct rkvdec_vp9_inter_frame_probs {
>  		u8 fr[2][3];
>  		u8 class0_hp[2];
>  		u8 hp[2];
> +		/* 32 bit alignment */
> +		u8 padding6[3];
>  	} mv;
>  };
>  
> @@ -85,7 +87,7 @@ struct rkvdec_vp9_probs {
>  		struct rkvdec_vp9_intra_only_frame_probs intra_only;
>  	};
>  	/* 128 bit alignment */
> -	u8 padding1[11];
> +	u8 padding1[8];
>  };
>  
>  /* Data structure describing auxiliary buffer format. */

Re: [PATCH] media: rkvdec: vp9: Fix probs struct alignment

Posted by Nicolas Dufresne 1 day, 7 hours ago

Le vendredi 12 décembre 2025 à 11:01 -0500, Detlev Casanova a écrit :
> When building for arm 32 bits, the struct alignment changes and the compiler
> adds 3 padding bits to the anonymous mv struct in
> rkvdec_vp9_inter_frame_probs.
> 
> Therefore, the BUILD_BUG_ON used to check that the struct size is aligned
> to 128 bits (hardware requirement) fails.
> 
> As that mv struct is at the end of the global rkvdec_vp9_probs struct
> and is followed by 11 padding bits, the 3 padding bits can be explicitely
> set in the mv struct and removed from the 11 following it.
> 
> This makes sure that the mv struct is 32 bits aligned.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes:
> https://lore.kernel.org/oe-kbuild-all/202512110229.R6YCf1Le-lkp@intel.com/
> Fixes: d968e50b5c26 ("media: rkvdec: Unstage the driver")
> Suggested-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

> ---
>  drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> index b4bf01e839ef..23c733ca2e8e 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec-vp9.c
> @@ -66,6 +66,8 @@ struct rkvdec_vp9_inter_frame_probs {
>  		u8 fr[2][3];
>  		u8 class0_hp[2];
>  		u8 hp[2];
> +		/* 32 bit alignment */
> +		u8 padding6[3];
>  	} mv;
>  };
>  
> @@ -85,7 +87,7 @@ struct rkvdec_vp9_probs {
>  		struct rkvdec_vp9_intra_only_frame_probs intra_only;
>  	};
>  	/* 128 bit alignment */
> -	u8 padding1[11];
> +	u8 padding1[8];
>  };
>  
>  /* Data structure describing auxiliary buffer format. */