Re: [PATCH v2 1/3] media: V3s: Add support for Allwinner CSI.

From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Yong Deng <yong.deng@magewell.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>, Chen-Yu Tsai <wens@csie.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Hans Verkuil <hverkuil@xs4all.nl>, Arnd Bergmann <arnd@arndb.de>,
	Hugues Fruchet <hugues.fruchet@st.com>,
	Yannick Fertre <yannick.fertre@st.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Benoit Parrot <bparrot@ti.com>,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Jean-Christophe Trotin <jean-christophe.trotin@st.com>,
	Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>,
	Minghsiu Tsai <minghsiu.tsai@mediatek.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com
Subject: Re: [PATCH v2 1/3] media: V3s: Add support for Allwinner CSI.
Date: Tue, 21 Nov 2017 16:48:27 +0100	[thread overview]
Message-ID: <20171121154827.5a35xa6zlqrrvkxx@flea.lan> (raw)
In-Reply-To: <1501131697-1359-2-git-send-email-yong.deng@magewell.com>

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Hi,

On Thu, Jul 27, 2017 at 01:01:35PM +0800, Yong Deng wrote:
> Allwinner V3s SoC have two CSI module. CSI0 is used for MIPI interface
> and CSI1 is used for parallel interface. This is not documented in
> datasheet but by testing and guess.
> 
> This patch implement a v4l2 framework driver for it.
> 
> Currently, the driver only support the parallel interface. MIPI-CSI2,
> ISP's support are not included in this patch.
> 
> Signed-off-by: Yong Deng <yong.deng@magewell.com>

Thanks again for this driver.

It seems like at least this iteration is behaving in a weird way with
DMA transfers for at least YU12 and NV12 (and I would assume YV12).

Starting a transfer of multiple frames in either of these formats,
using either ffmpeg (ffmpeg -f v4l2 -video_size 640x480 -framerate 30
-i /dev/video0 output.mkv) or yavta (yavta -c80 -p -F --skip 0 -f NV12
-s 640x480 $(media-c tl -e 'sun6i-csi')) will end up in a panic.

The panic seems to be generated with random data going into parts of
the kernel memory, the pattern being in my case something like
0x8287868a which is very odd (always around 0x88)

It turns out that when you cover the sensor, the values change to
around 0x28, so it really seems like it's pixels that have been copied
there.

I've looked quickly at the DMA setup, and it seems reasonable to
me. Do you have the same issue on your side? Have you been able to
test those formats using your hardware?

Given that they all are planar formats and YUYV and the likes work
just fine, maybe we can leave them aside for now?

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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