From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
kernel@collabora.com, linux-media@vger.kernel.org,
linux-rockchip@lists.infradead.org,
linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 19/24] media: rkvdec-h264: Add field decoding support
Date: Thu, 31 Mar 2022 09:40:18 -0400 [thread overview]
Message-ID: <ce1cbeab5e4a8a8338f2567f05af3226305410c7.camel@collabora.com> (raw)
In-Reply-To: <20220330151658.GV12805@kadam>
Le mercredi 30 mars 2022 à 18:16 +0300, Dan Carpenter a écrit :
> Yeah. I'm aboslutely fine with whatever you do. Some of the questions
> you're asking occurred to me too but I don't have the answers.
>
> > > > > > + for (i = 0; i < builder->num_valid; i++) {
> > > > > > + struct v4l2_h264_reference *ref;
> > > > > > + u8 dpb_valid;
> > > > > > + u8 bottom;
> > > > >
> > > > > These would be better as type bool.
> > > >
> > > > I never used a bool for bit operations before, but I guess that can work, thanks
> > > > for the suggestion. As this deviates from the original code, I suppose I should
> > > > make this a separate patch ?
> > >
> > > I just saw the name and wondered why it was a u8. bool does make more
> > > sense and works fine for the bitwise stuff. But I don't really care at
> > > all.
> >
> > I'll do that in v2, in same patch, looks minor enough. I think if using bool
> > could guaranty that only 1 or 0 is possible, it would be even better, but don't
> > think C works like this.
>
> I'm not sure I understand. If you assign "bool x = <any non-zero>;"
> then x is set to true. Do you want a static checker warning for if
> <any non-zero> can be something other than one or zero? The problem is
> that people sometimes deliberately do stuff like "bool x = var & 0xf0;".
> Smatch will complain if you assign a negative value to x.
>
> test.c:8 test() warn: assigning (-3) to unsigned variable 'x'
>
> It's supposed to print a warning if you used it to save error codes like:
>
> x = some_kernel_function();
>
> But it does not. :/ Something to investigate.
That would be an amazing catch, you might have seen a lot of:
x = !!(var & 0xf0)
For branches, it does no matter, but if you use x it like this dpb_valid
variable is used, not having 0 or 1 can lead to very surprising results. In the
end its used like this
set_reg(reg0, val | (x << N))
So using bool type can hint the analyzer that 0 or 1 was likely expected, while
currently an u8 would be ambiguous and lead to false positive if we were to
warn.
>
> regards,
> dan carpenter
>
next prev parent reply other threads:[~2022-03-31 13:40 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-28 19:59 [PATCH v1 00/24] H.264 Field Decoding Support for Frame-based Decoders Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 01/24] media: h264: Increase reference lists size to 32 Nicolas Dufresne
2022-03-29 8:25 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 02/24] media: doc: Document dual use of H.264 pic_num/frame_num Nicolas Dufresne
2022-03-29 8:32 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 03/24] media: h264: Avoid wrapping long_term_frame_idx Nicolas Dufresne
2022-03-29 8:35 ` Sebastian Fricke
2022-03-31 16:28 ` Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 04/24] media: h264: Store current picture fields Nicolas Dufresne
2022-03-29 9:07 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 05/24] media: h264: Store all fields into the unordered list Nicolas Dufresne
2022-03-29 12:57 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 06/24] media: v4l2: Trace calculated p/b0/b1 initial reflist Nicolas Dufresne
2022-03-29 15:08 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 07/24] media: h264: Sort p/b reflist using frame_num Nicolas Dufresne
2022-03-29 13:34 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 08/24] media: v4l2: Reorder field reflist Nicolas Dufresne
2022-03-29 13:54 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 09/24] media: v4l2-mem2mem: Fix typo in trace message Nicolas Dufresne
2022-03-29 13:57 ` Sebastian Fricke
2022-03-30 14:57 ` Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 10/24] media: v4l2-mem2mem: Trace on implicit un-hold Nicolas Dufresne
2022-03-29 13:58 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 11/24] media: videobuf2-v4l2: Warn on holding buffers without support Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 12/24] media: rkvdec: Stop overclocking the decoder Nicolas Dufresne
2022-03-29 15:15 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 13/24] media: rkvdec: h264: Fix reference frame_num wrap for second field Nicolas Dufresne
2022-03-29 15:17 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 14/24] media: rkvdec: h264: Fix dpb_valid implementation Nicolas Dufresne
2022-03-29 15:27 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 15/24] media: rkvdec: Enable capture buffer holding for H264 Nicolas Dufresne
2022-03-29 15:34 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 16/24] media: rkvdec: Ensure decoded resolution fit coded resolution Nicolas Dufresne
2022-03-29 15:39 ` Sebastian Fricke
2022-03-30 9:06 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 17/24] media: rkvdec: h264: Validate and use pic width and height in mbs Nicolas Dufresne
2022-03-30 6:48 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 18/24] media: rkvdec: h264: Fix bit depth wrap in pps packet Nicolas Dufresne
2022-03-30 6:59 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 19/24] media: rkvdec-h264: Add field decoding support Nicolas Dufresne
2022-03-29 8:13 ` Dan Carpenter
2022-03-29 20:54 ` Nicolas Dufresne
2022-03-30 5:15 ` Dan Carpenter
2022-03-30 13:39 ` Nicolas Dufresne
2022-03-30 15:16 ` Dan Carpenter
2022-03-31 13:40 ` Nicolas Dufresne [this message]
2022-03-30 7:10 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 20/24] media: hantro: Enable HOLD_CAPTURE_BUF for H.264 Nicolas Dufresne
2022-03-30 7:36 ` Sebastian Fricke
2022-03-31 18:25 ` Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 21/24] media: hantro: Stop using H.264 parameter pic_num Nicolas Dufresne
2022-03-30 7:42 ` Sebastian Fricke
2022-03-30 15:08 ` Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 22/24] media: hantro: h264: Make dpb entry management more robust Nicolas Dufresne
2022-03-30 7:59 ` Sebastian Fricke
2022-03-30 15:15 ` Nicolas Dufresne
2022-03-30 23:43 ` Ezequiel Garcia
2022-03-31 6:54 ` Sebastian Fricke
2022-03-28 19:59 ` [PATCH v1 23/24] media: hantro: Add H.264 field decoding support Nicolas Dufresne
2022-03-30 9:03 ` Sebastian Fricke
2022-03-30 15:25 ` Nicolas Dufresne
2022-03-28 19:59 ` [PATCH v1 24/24] media: rkvdec-h264: Don't hardcode SPS/PPS parameters Nicolas Dufresne
2022-03-29 7:22 ` Sebastian Fricke
2022-03-30 15:27 ` Nicolas Dufresne
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ce1cbeab5e4a8a8338f2567f05af3226305410c7.camel@collabora.com \
--to=nicolas.dufresne@collabora.com \
--cc=dan.carpenter@oracle.com \
--cc=ezequiel@vanguardiasur.com.ar \
--cc=gregkh@linuxfoundation.org \
--cc=kernel@collabora.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=linux-staging@lists.linux.dev \
--cc=mchehab@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).