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References: <20240507-cocci-flexarray-v2-0-7aea262cf065@chromium.org>
 <20240507-cocci-flexarray-v2-1-7aea262cf065@chromium.org> <Zjs9h40l9gfaiOei@pengutronix.de>
In-Reply-To: <Zjs9h40l9gfaiOei@pengutronix.de>
From: Ricardo Ribalda <ribalda@chromium.org>
Date: Thu, 9 May 2024 20:50:14 +0200
Message-ID: <CANiDSCvon2eW4aHk8JD2_GDR9hG1FBhgbCOEZ+W2RC2HHsXM5A@mail.gmail.com>
Subject: Re: [PATCH v2 01/18] media: allegro: nal-hevc: Refactor nal_hevc_sub_layer_hrd_parameters
To: Michael Tretter <m.tretter@pengutronix.de>, Ricardo Ribalda <ribalda@chromium.org>, 
	Pengutronix Kernel Team <kernel@pengutronix.de>, Mauro Carvalho Chehab <mchehab@kernel.org>, 
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Michal Simek <michal.simek@amd.com>, 
	Andy Walls <awalls@md.metrocast.net>, Stanimir Varbanov <stanimir.k.varbanov@gmail.com>, 
	Vikash Garodia <quic_vgarodia@quicinc.com>, "Bryan O'Donoghue" <bryan.odonoghue@linaro.org>, 
	Bjorn Andersson <andersson@kernel.org>, Konrad Dybcio <konrad.dybcio@linaro.org>, 
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, 
	Hans Verkuil <hverkuil-cisco@xs4all.nl>
Content-Type: text/plain; charset="UTF-8"

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