[BUG REPORT] media: coda: mpeg4 decode corruption on i.MX6qp only

[Sven Van Asbroeck]

From: Sven Van Asbroeck <thesven73@xxxxxxxxx>

We have observed that under certain repeatable circumstances, the CODA
mem2mem device consistently generates corrupted frames. This happens only
on an i.MX6qp (Plus) - the classic imx6q is not affected.

This happens when the virtual X screen is wider than 0x900 pixels (1).

Quite strange, because CODA is a mem2mem device, and is presumably not touching
any of the IPU/GPU2D/GPU3D infrastructure used by X. Except if there is a hidden
dependency somehow.

I have captured and visualized generated CODA frames as follows:
gst-launch-1.0 playbin uri=file:///home/default/nycTrain1080p.mp4 flags=0x45
    video-sink='multifilesink location=frame%d.yuv'
See (2) for how I converted the raw YUV frame to a PNG image.

For example, the following will break CODA mpeg4 decode (width >= 0x900):
# xrandr --fb 2400x1088
Screen 0: minimum 1 x 1, current 2400 x 1088, maximum 4096 x 4096
HDMI1 disconnected (normal left inverted right x axis y axis)
LVDS1 connected primary 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1280x800      59.79*+

Resulting frame when dumped with multifilesink (NOT written to the display):
https://gitlab.com/TheSven73/coda-investigation/-/blob/master/stripes.png

And the following will restore CODA mpeg4 decode (width < 0x900):
# xrandr --fb 2300x1088
Screen 0: minimum 1 x 1, current 2300 x 1088, maximum 4096 x 4096
HDMI1 disconnected (normal left inverted right x axis y axis)
LVDS1 connected primary 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1280x800      59.79*+

Resulting frame when dumped with multifilesink (NOT written to the display):
https://gitlab.com/TheSven73/coda-investigation/-/blob/master/ok.png

Additional info:
- only the virtual X screen width seems to trigger the issue, it is
  independent of the height.
- issue seems independent of the pixel format. Forcing CODA to output NV12
  shows the same behaviour.

System description:
- i.MX6 QuadPlus:
[    0.144518] CPU identified as i.MX6QP, silicon rev 1.1
- mainline Linux v5.9.16 with a small private patchset on top
  (patchset does not touch CODA)
- CODA960 silicon contained within i.MX6 QuadPlus:
[ 4798.510033] coda 2040000.vpu: Firmware code revision: 46076
[ 4798.515916] coda 2040000.vpu: Initialized CODA960.
[ 4798.520779] coda 2040000.vpu: Firmware version: 3.1.1
- gstreamer from buildroot:
gst-launch-1.0 version 1.16.2
GStreamer 1.16.2
- X from buildroot, using armada and etnadrm_gpu plugins:
X.Org X Server 1.20.7
X Protocol Version 11, Revision 0
[    99.527] (II) LoadModule: "armada"
[    99.527] (II) Loading /usr/lib/xorg/modules/drivers/armada_drv.so
[    99.538] (II) Module armada: vendor="X.Org Foundation"
[    99.538] 	compiled for 1.20.7, module version = 0.0.0
[    99.538] 	Module class: X.Org Video Driver
[    99.538] 	ABI class: X.Org Video Driver, version 24.1
[    99.538] (II) armada: Support for Marvell LCD Controller: 88AP510
[    99.539] (II) armada: Support for Freescale IPU: i.MX6
[    99.545] (II) armada(0): Added screen for KMS device /dev/dri/card1
[    99.561] (II) armada(0): hardware: imx-drm
[    99.563] (**) armada(0): Option "AccelModule" "etnadrm_gpu"
[    99.563] (II) Loading sub module "etnadrm_gpu"
[    99.563] (II) LoadModule: "etnadrm_gpu"
[    99.564] (II) Loading /usr/lib/xorg/modules/drivers/etnadrm_gpu.so
[    99.576] (II) Module Etnaviv GPU driver (DRM): vendor="X.Org Foundation"
[    99.576] 	compiled for 1.20.7, module version = 0.0.0


(1) When using multiple displays, the virtual X screen is typically the bounding
    rectangle which includes all screens. That's why it can become wider than
    1920 pixels.

(2)

# Convert raw YUYV to PNG
# Python, runs out of the box on a stock Google Colab notebook
import cv2
import numpy as np
import matplotlib.pyplot as plt
import matplotlib

img = np.fromfile('frame1.yuv', dtype=np.uint8)
# YUYV has two 8-bit channels per pixel
img.shape = (1088, 1920, 2)

img2 = cv2.cvtColor(img, cv2.COLOR_YUV2RGB_YUYV)
plt.imshow(img2)
matplotlib.image.imsave('frame1.png', img2)

To: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
To: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Cc: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Fabio Estevam <festevam@xxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx