[PATCH v6 4/8] media: platform: Add Cedrus VPU decoder driver

On Wed, 2018-07-25 at 12:02 +0200, Paul Kocialkowski wrote:

This introduces the Cedrus VPU driver that supports the VPU found in
Allwinner SoCs, also known as Video Engine. It is implemented through
a v4l2 m2m decoder device and a media device (used for media requests).
So far, it only supports MPEG2 decoding.

Since this VPU is stateless, synchronization with media requests is
required in order to ensure consistency between frame headers that
contain metadata about the frame to process and the raw slice data that
is used to generate the frame.

This driver was made possible thanks to the long-standing effort
carried out by the linux-sunxi community in the interest of reverse
engineering, documenting and implementing support for Allwinner VPU.

Signed-off-by: Paul Kocialkowski <redacted>

[..]

+static int cedrus_probe(struct platform_device *pdev)
+{
+	struct cedrus_dev *dev;
+	struct video_device *vfd;
+	int ret;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->dev = &pdev->dev;
+	dev->pdev = pdev;
+
+	ret = cedrus_hw_probe(dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to probe hardware\n");
+		return ret;
+	}
+
+	dev->dec_ops[CEDRUS_CODEC_MPEG2] = &cedrus_dec_ops_mpeg2;
+
+	mutex_init(&dev->dev_mutex);
+	spin_lock_init(&dev->irq_lock);
+

A minor thing.

I believe this spinlock is not needed. All the data structures
it's accessing are already protected, and some operations
(stop_streaming) are guaranteed to not run at the same
time as a job.

Regards,
Eze