[v2,01/18] media: allegro: nal-hevc: Refactor nal_hevc_sub_layer_hrd_parameters

  Replace all the single elements arrays with the element itself.

Pahole shows the same padding and alignment for x86 and arm in both
situations.

This fixes this cocci warning:
drivers/media/platform/allegro-dvt/nal-hevc.h:102:14-22: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/platform/allegro-dvt/allegro-core.c |  6 +++---
 drivers/media/platform/allegro-dvt/nal-hevc.c     | 11 +++--------
 drivers/media/platform/allegro-dvt/nal-hevc.h     |  6 +++---
 3 files changed, 9 insertions(+), 14 deletions(-)
  

On Tue, 07 May 2024 16:27:06 +0000, Ricardo Ribalda wrote:
> Replace all the single elements arrays with the element itself.
> 
> Pahole shows the same padding and alignment for x86 and arm in both
> situations.
> 
> This fixes this cocci warning:
> drivers/media/platform/allegro-dvt/nal-hevc.h:102:14-22: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)

Thanks for the patch.

> 
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/platform/allegro-dvt/allegro-core.c |  6 +++---
>  drivers/media/platform/allegro-dvt/nal-hevc.c     | 11 +++--------
>  drivers/media/platform/allegro-dvt/nal-hevc.h     |  6 +++---
>  3 files changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/media/platform/allegro-dvt/allegro-core.c b/drivers/media/platform/allegro-dvt/allegro-core.c
> index da61f9beb6b4..369bd88cc0ae 100644
> --- a/drivers/media/platform/allegro-dvt/allegro-core.c
> +++ b/drivers/media/platform/allegro-dvt/allegro-core.c
> @@ -1852,14 +1852,14 @@ static ssize_t allegro_hevc_write_sps(struct allegro_channel *channel,
>  	hrd->dpb_output_delay_length_minus1 = 30;
>  
>  	hrd->bit_rate_scale = ffs(channel->bitrate_peak) - 6;
> -	hrd->vcl_hrd[0].bit_rate_value_minus1[0] =
> +	hrd->vcl_hrd[0].bit_rate_value_minus1 =
>  		(channel->bitrate_peak >> (6 + hrd->bit_rate_scale)) - 1;
>  
>  	cpb_size = v4l2_ctrl_g_ctrl(channel->mpeg_video_cpb_size) * 1000;
>  	hrd->cpb_size_scale = ffs(cpb_size) - 4;
> -	hrd->vcl_hrd[0].cpb_size_value_minus1[0] = (cpb_size >> (4 + hrd->cpb_size_scale)) - 1;
> +	hrd->vcl_hrd[0].cpb_size_value_minus1 = (cpb_size >> (4 + hrd->cpb_size_scale)) - 1;
>  
> -	hrd->vcl_hrd[0].cbr_flag[0] = !v4l2_ctrl_g_ctrl(channel->mpeg_video_frame_rc_enable);
> +	hrd->vcl_hrd[0].cbr_flag = !v4l2_ctrl_g_ctrl(channel->mpeg_video_frame_rc_enable);
>  
>  	size = nal_hevc_write_sps(&dev->plat_dev->dev, dest, n, sps);
>  
> diff --git a/drivers/media/platform/allegro-dvt/nal-hevc.c b/drivers/media/platform/allegro-dvt/nal-hevc.c
> index 9cdf2756e0a3..575089522df5 100644
> --- a/drivers/media/platform/allegro-dvt/nal-hevc.c
> +++ b/drivers/media/platform/allegro-dvt/nal-hevc.c
> @@ -210,14 +210,9 @@ static void nal_hevc_rbsp_vps(struct rbsp *rbsp, struct nal_hevc_vps *vps)
>  static void nal_hevc_rbsp_sub_layer_hrd_parameters(struct rbsp *rbsp,
>  						   struct nal_hevc_sub_layer_hrd_parameters *hrd)
>  {
> -	unsigned int i;
> -	unsigned int cpb_cnt = 1;
> -
> -	for (i = 0; i < cpb_cnt; i++) {
> -		rbsp_uev(rbsp, &hrd->bit_rate_value_minus1[i]);
> -		rbsp_uev(rbsp, &hrd->cpb_size_value_minus1[i]);
> -		rbsp_bit(rbsp, &hrd->cbr_flag[i]);
> -	}
> +	rbsp_uev(rbsp, &hrd->bit_rate_value_minus1);
> +	rbsp_uev(rbsp, &hrd->cpb_size_value_minus1);
> +	rbsp_bit(rbsp, &hrd->cbr_flag);
>  }
>  
>  static void nal_hevc_rbsp_hrd_parameters(struct rbsp *rbsp,
> diff --git a/drivers/media/platform/allegro-dvt/nal-hevc.h b/drivers/media/platform/allegro-dvt/nal-hevc.h
> index eb46f12aae80..afa7a9d7d654 100644
> --- a/drivers/media/platform/allegro-dvt/nal-hevc.h
> +++ b/drivers/media/platform/allegro-dvt/nal-hevc.h
> @@ -97,9 +97,9 @@ struct nal_hevc_vps {
>  };
>  
>  struct nal_hevc_sub_layer_hrd_parameters {
> -	unsigned int bit_rate_value_minus1[1];
> -	unsigned int cpb_size_value_minus1[1];
> -	unsigned int cbr_flag[1];
> +	unsigned int bit_rate_value_minus1;
> +	unsigned int cpb_size_value_minus1;
> +	unsigned int cbr_flag;

The struct is modeled after the specification in ITU-T H.265, which
defines the fields as arrays. It's a limitation of the current
implementation that only a single element is supported.

Maybe replacing the hard coded values with a constant would be more
appropriate to document this limitation.

Michael

>  };
>  
>  struct nal_hevc_hrd_parameters {
> 
> -- 
> 2.45.0.rc1.225.g2a3ae87e7f-goog
> 
>
  

Hi Michael

On Wed, 8 May 2024 at 10:53, Michael Tretter <m.tretter@pengutronix.de> wrote:
>
> On Tue, 07 May 2024 16:27:06 +0000, Ricardo Ribalda wrote:
> > Replace all the single elements arrays with the element itself.
> >
> > Pahole shows the same padding and alignment for x86 and arm in both
> > situations.
> >
> > This fixes this cocci warning:
> > drivers/media/platform/allegro-dvt/nal-hevc.h:102:14-22: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
>
> Thanks for the patch.
>
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/platform/allegro-dvt/allegro-core.c |  6 +++---
> >  drivers/media/platform/allegro-dvt/nal-hevc.c     | 11 +++--------
> >  drivers/media/platform/allegro-dvt/nal-hevc.h     |  6 +++---
> >  3 files changed, 9 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/media/platform/allegro-dvt/allegro-core.c b/drivers/media/platform/allegro-dvt/allegro-core.c
> > index da61f9beb6b4..369bd88cc0ae 100644
> > --- a/drivers/media/platform/allegro-dvt/allegro-core.c
> > +++ b/drivers/media/platform/allegro-dvt/allegro-core.c
> > @@ -1852,14 +1852,14 @@ static ssize_t allegro_hevc_write_sps(struct allegro_channel *channel,
> >       hrd->dpb_output_delay_length_minus1 = 30;
> >
> >       hrd->bit_rate_scale = ffs(channel->bitrate_peak) - 6;
> > -     hrd->vcl_hrd[0].bit_rate_value_minus1[0] =
> > +     hrd->vcl_hrd[0].bit_rate_value_minus1 =
> >               (channel->bitrate_peak >> (6 + hrd->bit_rate_scale)) - 1;
> >
> >       cpb_size = v4l2_ctrl_g_ctrl(channel->mpeg_video_cpb_size) * 1000;
> >       hrd->cpb_size_scale = ffs(cpb_size) - 4;
> > -     hrd->vcl_hrd[0].cpb_size_value_minus1[0] = (cpb_size >> (4 + hrd->cpb_size_scale)) - 1;
> > +     hrd->vcl_hrd[0].cpb_size_value_minus1 = (cpb_size >> (4 + hrd->cpb_size_scale)) - 1;
> >
> > -     hrd->vcl_hrd[0].cbr_flag[0] = !v4l2_ctrl_g_ctrl(channel->mpeg_video_frame_rc_enable);
> > +     hrd->vcl_hrd[0].cbr_flag = !v4l2_ctrl_g_ctrl(channel->mpeg_video_frame_rc_enable);
> >
> >       size = nal_hevc_write_sps(&dev->plat_dev->dev, dest, n, sps);
> >
> > diff --git a/drivers/media/platform/allegro-dvt/nal-hevc.c b/drivers/media/platform/allegro-dvt/nal-hevc.c
> > index 9cdf2756e0a3..575089522df5 100644
> > --- a/drivers/media/platform/allegro-dvt/nal-hevc.c
> > +++ b/drivers/media/platform/allegro-dvt/nal-hevc.c
> > @@ -210,14 +210,9 @@ static void nal_hevc_rbsp_vps(struct rbsp *rbsp, struct nal_hevc_vps *vps)
> >  static void nal_hevc_rbsp_sub_layer_hrd_parameters(struct rbsp *rbsp,
> >                                                  struct nal_hevc_sub_layer_hrd_parameters *hrd)
> >  {
> > -     unsigned int i;
> > -     unsigned int cpb_cnt = 1;
> > -
> > -     for (i = 0; i < cpb_cnt; i++) {
> > -             rbsp_uev(rbsp, &hrd->bit_rate_value_minus1[i]);
> > -             rbsp_uev(rbsp, &hrd->cpb_size_value_minus1[i]);
> > -             rbsp_bit(rbsp, &hrd->cbr_flag[i]);
> > -     }
> > +     rbsp_uev(rbsp, &hrd->bit_rate_value_minus1);
> > +     rbsp_uev(rbsp, &hrd->cpb_size_value_minus1);
> > +     rbsp_bit(rbsp, &hrd->cbr_flag);
> >  }
> >
> >  static void nal_hevc_rbsp_hrd_parameters(struct rbsp *rbsp,
> > diff --git a/drivers/media/platform/allegro-dvt/nal-hevc.h b/drivers/media/platform/allegro-dvt/nal-hevc.h
> > index eb46f12aae80..afa7a9d7d654 100644
> > --- a/drivers/media/platform/allegro-dvt/nal-hevc.h
> > +++ b/drivers/media/platform/allegro-dvt/nal-hevc.h
> > @@ -97,9 +97,9 @@ struct nal_hevc_vps {
> >  };
> >
> >  struct nal_hevc_sub_layer_hrd_parameters {
> > -     unsigned int bit_rate_value_minus1[1];
> > -     unsigned int cpb_size_value_minus1[1];
> > -     unsigned int cbr_flag[1];
> > +     unsigned int bit_rate_value_minus1;
> > +     unsigned int cpb_size_value_minus1;
> > +     unsigned int cbr_flag;
>
> The struct is modeled after the specification in ITU-T H.265, which
> defines the fields as arrays. It's a limitation of the current
> implementation that only a single element is supported.
>
> Maybe replacing the hard coded values with a constant would be more
> appropriate to document this limitation.

A define seems to convince coccinelle of our intentions :). I will
upload the fix in v3

diff --git a/drivers/media/platform/allegro-dvt/nal-hevc.h
b/drivers/media/platform/allegro-dvt/nal-hevc.h
index eb46f12aae80..361e2f55c254 100644
--- a/drivers/media/platform/allegro-dvt/nal-hevc.h
+++ b/drivers/media/platform/allegro-dvt/nal-hevc.h
@@ -96,10 +96,11 @@ struct nal_hevc_vps {
        unsigned int extension_data_flag;
 };

+#define N_HRD_PARAMS 1
 struct nal_hevc_sub_layer_hrd_parameters {
-       unsigned int bit_rate_value_minus1[1];
-       unsigned int cpb_size_value_minus1[1];
-       unsigned int cbr_flag[1];
+       unsigned int bit_rate_value_minus1[N_HRD_PARAMS];
+       unsigned int cpb_size_value_minus1[N_HRD_PARAMS];
+       unsigned int cbr_flag[N_HRD_PARAMS];
 };

 struct nal_hevc_hrd_parameters {


Thanks.


>
> Michael
>
> >  };
> >
> >  struct nal_hevc_hrd_parameters {
> >
> > --
> > 2.45.0.rc1.225.g2a3ae87e7f-goog
> >
> >



--
Ricardo Ribalda