From: Dan Carpenter <error27@gmail.com>
To: Michael Freidkin <freidkin@gmail.com>
Cc: Neil Armstrong <neil.armstrong@linaro.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kevin Hilman <khilman@baylibre.com>,
Jerome Brunet <jbrunet@baylibre.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
linux-media@vger.kernel.org, linux-amlogic@lists.infradead.org,
linux-staging@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] media: meson: vdec: size capture planes from the aligned canvas
Date: Tue, 29 Sep 2026 08:46:45 +0300 [thread overview]
Message-ID: <artQxRR3kJUv-mBF@stanley.mountain> (raw)
In-Reply-To: <20260928165045.642354-1-freidkin@gmail.com>
On Mon, Sep 28, 2026 at 07:50:45PM +0300, Michael Freidkin wrote:
> The decoder writes a whole canvas of ALIGN(width, 32) x ALIGN(height, 32)
> (amvdec_set_canvases()) and reports bytesperline = ALIGN(width, 32), but
> get_output_size() derives sizeimage from the raw width x height.
>
> When the width is not a multiple of 32 the planes are too small for the
> advertised stride: for 720x360 NV12M the luma plane is 262144 bytes while
> 736 * 360 = 264960 are needed (282624 for the canvas the firmware fills).
> The decoder writes past the buffer, and importing the capture dma-buf
> into DRM fails: drmModeAddFB2() returns -EINVAL, so e.g. Kodi plays the
> sound over a black screen. 1280x720 and 1920x1080 are not affected.
>
> Size the planes from the aligned canvas the hardware actually uses.
>
> Tested on an S905X (GXL p212) board with LibreELEC 12 (6.16.0-rc3):
> 720x360 and 1920x1080 H.264 play through V4L2 m2m + DRM PRIME with no
> AddFB2 errors.
>
> Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
> Signed-off-by: Michael Freidkin <freidkin@gmail.com>
Reviewed-by: Dan Carpenter <error27@gmail.com>
It would probably be more reliable to just ALIGN() the width and
height at the start so we don't have to do it over and over again.
regards,
dan carpenter
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next prev parent reply other threads:[~2026-09-29 5:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-28 16:50 Michael Freidkin
2026-09-29 5:46 ` Dan Carpenter [this message]
2026-09-29 6:08 ` Michael Freidkin
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