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 <20230525021219.23638-9-yunfei.dong@mediatek.com> <f3322e41-1891-a33b-daaa-731ec548ec4e@collabora.com>
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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Tue, 30 May 2023 18:15:07 +0800
Message-ID: <CAGXv+5FFS6cC+drzXfAbtoEq8b_-9sA1Ry4Xb74hndCkCNiSSA@mail.gmail.com>
Subject: Re: [PATCH v5,8/8] media: mediatek: vcodec: Add dbgfs help function
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Cc:     Yunfei Dong <yunfei.dong@mediatek.com>,
        Nicolas Dufresne <nicolas.dufresne@collabora.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Benjamin Gaignard <benjamin.gaignard@collabora.com>,
        =?UTF-8?B?TsOtY29sYXMgRiAuIFIgLiBBIC4gUHJhZG8=?= 
        <nfraprado@collabora.com>, Nathan Hebert <nhebert@chromium.org>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Fritz Koenig <frkoenig@chromium.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Steve Cho <stevecho@chromium.org>, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com
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On Tue, May 30, 2023 at 6:06=E2=80=AFPM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> Il 25/05/23 04:12, Yunfei Dong ha scritto:
> > Getting dbgfs help information with command "echo -help > vdec".
> >
> > Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
> > ---
> >   .../mediatek/vcodec/mtk_vcodec_dbgfs.c        | 24 ++++++++++++++++++=
-
> >   1 file changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c =
b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> > index 237d0dc8a1fc..2372fc449b45 100644
> > --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> > +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> > @@ -52,6 +52,23 @@ static void mtk_vdec_dbgfs_get_format_type(struct mt=
k_vcodec_ctx *ctx, char *buf
> >       *used +=3D curr_len;
> >   }
> >
> > +static void mtk_vdec_dbgfs_get_help(char *buf, int *used, int total)
> > +{
> > +     int curr_len;
> > +
> > +     curr_len =3D snprintf(buf + *used, total - *used,
> > +                         "help: (1: echo -'info' > vdec 2: cat vdec)\n=
");
> > +     *used +=3D curr_len;
> > +
> > +     curr_len =3D snprintf(buf + *used, total - *used,
> > +                         "\t-picinfo: get resolution\n");
> > +     *used +=3D curr_len;
> > +
> > +     curr_len =3D snprintf(buf + *used, total - *used,
> > +                         "\t-format: get output & capture queue format=
\n");
> > +     *used +=3D curr_len;
> > +}
> > +
> >   static ssize_t mtk_vdec_dbgfs_write(struct file *filp, const char __u=
ser *ubuf,
> >                                   size_t count, loff_t *ppos)
> >   {
> > @@ -84,6 +101,11 @@ static ssize_t mtk_vdec_dbgfs_read(struct file *fil=
p, char __user *ubuf,
> >       if (!buf)
> >               return -ENOMEM;
> >
> > +     if (strstr(dbgfs->dbgfs_buf, "-help")) {
>
> I would print the help strings in two conditions:
> 1. -help
> 2. (nothing)
>
> ...so that if you don't echo anything to vdec (no params), you get the he=
lp text.
> Otherwise, you would have to know that "-help" is a parameter that gives =
you help
> text in the first place.
>
> As for this commit "as is", it works as intended and it is useful to retr=
ieve
> the help text; you can either send a followup commit that extends the hel=
p to
> the corner case that I've explained, or send a v6 adding that to this sam=
e commit.
>
> I would prefer to see a v6 -- BUT -- since this series was sent a long ti=
me ago,
> you will get my R-b and I will leave the final choice to Hans.
>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collab=
ora.com>

The help file could just exist as a separate file. You can then use cleaner
interfaces for it.

ChenYu