From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Tomasz Figa <tfiga@chromium.org>,
Hans Verkuil <hans.verkuil@cisco.com>,
Alexandre Courbot <acourbot@chromium.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Pawel Osciak <posciak@chromium.org>,
Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
Chen-Yu Tsai <wens@csie.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
Joerg Roedel <joro@8bytes.org>,"
<linux-arm-kernel@lists.infradead.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Nicolas Dufresne <nicolas.dufresne@collabora.com>,
jenskuske@gmail.com, Jernej Skrabec <jernej.skrabec@gmail.com>,
Jonas Karlman <jonas@kwiboo.se>,
linux-sunxi@googlegroups.com,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH v3 0/2] media: cedrus: Add H264 decoding support
Date: Thu, 14 Feb 2019 16:47:56 +0100 [thread overview]
Message-ID: <20190214154756.iirejyrmqrtfjr3e@flea> (raw)
In-Reply-To: <2e468fd22b577f1a5fd5d3186d6cc88e442e07ec.camel@collabora.com>
On Wed, Feb 13, 2019 at 01:28:34PM -0300, Ezequiel Garcia wrote:
> On Wed, 2019-02-13 at 12:02 +0900, Tomasz Figa wrote:
> > On Wed, Feb 13, 2019 at 6:22 AM Ezequiel Garcia <ezequiel@collabora.com> wrote:
> > > Hey Tomasz,
> > >
> > > On Tue, 2019-02-12 at 21:50 +0900, Tomasz Figa wrote:
> > > > Hi Maxime,
> > > >
> > > > On Mon, Feb 11, 2019 at 11:39 PM Maxime Ripard
> > > > <maxime.ripard@bootlin.com> wrote:
> > > > > Hi,
> > > > >
> > > > > Here is a new version of the H264 decoding support in the cedrus
> > > > > driver.
> > > >
> > > > Thanks for working on this. Please see my comments below.
> > > >
> > > > > As you might already know, the cedrus driver relies on the Request
> > > > > API, and is a reverse engineered driver for the video decoding engine
> > > > > found on the Allwinner SoCs.
> > > > >
> > > > > This work has been possible thanks to the work done by the people
> > > > > behind libvdpau-sunxi found here:
> > > > > https://github.com/linux-sunxi/libvdpau-sunxi/
> > > > >
> > > > > I've tested the various ABI using this gdb script:
> > > > > http://code.bulix.org/jl4se4-505620?raw
> > > > >
> > > > > And this test script:
> > > > > http://code.bulix.org/8zle4s-505623?raw
> > > > >
> > > > > The application compiled is quite trivial:
> > > > > http://code.bulix.org/e34zp8-505624?raw
> > > > >
> > > > > The output is:
> > > > > arm: builds/arm-test-v4l2-h264-structures
> > > > > SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> > > > > x86: builds/x86-test-v4l2-h264-structures
> > > > > SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> > > > > x64: builds/x64-test-v4l2-h264-structures
> > > > > SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> > > > > arm64: builds/arm64-test-v4l2-h264-structures
> > > > > SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> > > > >
> > > > > Let me know if there's any flaw using that test setup, or if you have
> > > > > any comments on the patches.
> > > > >
> > > > > Maxime
> > > > >
> > > > > Changes from v2:
> > > > > - Simplified _cedrus_write_ref_list as suggested by Jernej
> > > > > - Set whether the frame is used as reference using nal_ref_idc
> > > > > - Respect chroma_format_idc
> > > > > - Fixes for the scaling list and prediction tables
> > > > > - Wrote the documentation for the flags
> > > > > - Added a bunch of defines to the driver bit fields
> > > > > - Reworded the controls and data format descriptions as suggested
> > > > > by Hans
> > > > > - Reworked the controls' structure field size to avoid padding
> > > > > - Removed the long term reference flag
> > > >
> > > > This and...
> > > >
> > >
> > > Maxime has dropped this because of Ayaka's mail about long term references
> > > not making much sense in stateless decoders.
> >
> > I haven't seen any argument confirming that thesis, though. I should
> > have kicked in earlier, sorry.
> >
>
> OK, in that case, we need to have this flag back.
>
> > > I noticed that RK3399 TRM has a field to specify long term refs and
> > > so was wondering about this item as well.
> > >
> > > > > - Reintroduced the neighbor info buffer
> > > > > - Removed the ref_pic_list_p0/b0/b1 arrays that are redundant with the
> > > > > one in the DPB
> > > >
> > > > these are used in our Rockchip VDEC driver.
> > > >
> > > > Could you elaborate on the reasons why they got removed?
> > > >
> > >
> > > If I understood correctly, there are two reference picture lists.
> > > P-frames will populate ref_pic_list0 and B-frames will populate both.
> > >
> > > According to this, v4l2_ctrl_h264_slice_param.ref_pic_list0 and .ref_pic_list1
> > > should be enough and ref_pic_list_p0/b0/b1 are not needed.
> > >
> > > What do you think?
> >
> > The lists in v4l2_ctrl_h264_slice_param are expected to be past the
> > per-slice modification stage (which is quite complicated and better
> > done in userspace),
>
> The fact that these are RefPicList0 and RefPicList1, after
> the reordering stage should be better documented.
>
> > while the ones in v4l2_ctrl_h264_decode_param just
> > in the original order. Rockchip VPU expects them in the original order
> > and does the modification in the hardware.
> >
>
> OK, I see.
>
> So, we have RefPicList0 and RefPicList1, and there is an initialization
> stage and a modification/reordering process.
>
> One could argue that it's more generic to just pass the initial list,
> but that would mean doing in the kernel something that is easier
> done in userspace (and parsers doing this are already available).
>
> The question would be what is the most generic way of passing
> the RefPicList0 and RefPicList1 in its initial state.
>
> 1/ We create additional controls for these.
>
> 2/ We put them on some of the other controls. Putting them on
> v4l2_ctrl_h264_decode_param didn't seem too wrong.
>
> Any objections to put them back in there?
None. i'll put them back in.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
prev parent reply other threads:[~2019-02-14 15:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 14:39 [PATCH v3 0/2] media: cedrus: Add H264 decoding support Maxime Ripard
2019-02-11 14:39 ` [PATCH v3 1/2] media: uapi: Add H264 low-level decoder API compound controls Maxime Ripard
2019-02-11 15:16 ` Hans Verkuil
2019-02-11 15:21 ` Hans Verkuil
2019-02-12 13:05 ` Maxime Ripard
2019-02-12 21:17 ` Ezequiel Garcia
2019-02-11 17:16 ` Nicolas Dufresne
2019-02-11 17:12 ` Ezequiel Garcia
2019-02-12 10:23 ` Maxime Ripard
2019-02-11 19:53 ` Ezequiel Garcia
2019-02-11 14:39 ` [PATCH v3 2/2] media: cedrus: Add H264 decoding support Maxime Ripard
2019-02-11 19:21 ` [linux-sunxi] " Jernej Škrabec
2019-02-12 10:43 ` Maxime Ripard
2019-02-12 17:46 ` Jernej Škrabec
2019-02-11 19:48 ` Ezequiel Garcia
2019-02-12 12:47 ` Maxime Ripard
2019-02-12 17:40 ` Jernej Škrabec
2019-02-14 20:42 ` Jernej Škrabec
2019-02-14 21:27 ` Jernej Škrabec
2019-02-12 12:50 ` [PATCH v3 0/2] " Tomasz Figa
2019-02-12 21:22 ` Ezequiel Garcia
2019-02-13 3:02 ` Tomasz Figa
2019-02-13 16:28 ` Ezequiel Garcia
2019-02-14 15:47 ` Maxime Ripard [this message]
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