Hi Tiffany,

A small review comment below:

On 02/04/2016 12:34 PM, Tiffany Lin wrote:

The VPU driver for hw video codec embedded in Mediatek's MT8173 SOCs.
It is able to handle video decoding/encoding of in a range of formats.
The driver provides with VPU firmware download, memory management and
the communication interface between CPU and VPU.
For VPU initialization, it will create virtual memory for CPU access and
IOMMU address for vcodec hw device access. When a decode/encode instance
opens a device node, vpu driver will download vpu firmware to the device.
A decode/encode instant will decode/encode a frame using VPU
interface to interrupt vpu to handle decoding/encoding jobs.

Signed-off-by: Andrew-CT Chen <andrew-ct.chen@mediatek.com>
Signed-off-by: Tiffany Lin <tiffany.lin@mediatek.com>
---
 drivers/media/platform/Kconfig           |    9 +
 drivers/media/platform/Makefile          |    2 +
 drivers/media/platform/mtk-vpu/Makefile  |    1 +
 drivers/media/platform/mtk-vpu/mtk_vpu.c |  994 ++++++++++++++++++++++++++++++
 drivers/media/platform/mtk-vpu/mtk_vpu.h |  167 +++++
 5 files changed, 1173 insertions(+)
 create mode 100644 drivers/media/platform/mtk-vpu/Makefile
 create mode 100644 drivers/media/platform/mtk-vpu/mtk_vpu.c
 create mode 100644 drivers/media/platform/mtk-vpu/mtk_vpu.h

<snip>

<snip>

+static ssize_t vpu_debug_read(struct file *file, char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	char buf[256];
+	unsigned int len;
+	unsigned int running, pc, vpu_to_host, host_to_vpu, wdt;
+	int ret;
+	struct device *dev = file->private_data;
+	struct mtk_vpu *vpu = dev_get_drvdata(dev);
+
+	ret = vpu_clock_enable(vpu);
+	if (ret) {
+		dev_err(vpu->dev, "[VPU] enable clock failed %d\n", ret);
+		return 0;
+	}
+
+	/* vpu register status */
+	running = vpu_running(vpu);
+	pc = vpu_cfg_readl(vpu, VPU_PC_REG);
+	wdt = vpu_cfg_readl(vpu, VPU_WDT_REG);
+	host_to_vpu = vpu_cfg_readl(vpu, HOST_TO_VPU);
+	vpu_to_host = vpu_cfg_readl(vpu, VPU_TO_HOST);
+	vpu_clock_disable(vpu);
+
+	if (running) {
+		len = sprintf(buf, "VPU is running\n\n"

Please use snprintf.

+		"FW Version: %s\n"
+		"PC: 0x%x\n"
+		"WDT: 0x%x\n"
+		"Host to VPU: 0x%x\n"
+		"VPU to Host: 0x%x\n",
+		vpu->run.fw_ver, pc, wdt,
+		host_to_vpu, vpu_to_host);
+	} else {
+		len = sprintf(buf, "VPU not running\n");

Ditto.

sprintf always makes me feel uncomfortable :-)

+	}
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}

Regards,

	Hans