linux-kernel - Re: [PATCH v4 2/8] [media] VPU: mediatek: support Mediatek VPU

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Message-ID: <56C1A36D.6010908@xs4all.nl>
Date:	Mon, 15 Feb 2016 11:07:41 +0100
From:	Hans Verkuil <hverkuil@...all.nl>
To:	Tiffany Lin <tiffany.lin@...iatek.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	daniel.thompson@...aro.org, Rob Herring <robh+dt@...nel.org>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Pawel Osciak <posciak@...omium.org>
Cc:	Eddie Huang <eddie.huang@...iatek.com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
	linux-mediatek@...ts.infradead.org, PoChun.Lin@...iatek.com,
	Andrew-CT Chen <andrew-ct.chen@...iatek.com>
Subject: Re: [PATCH v4 2/8] [media] VPU: mediatek: support Mediatek VPU

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@...iatek.com>
> Signed-off-by: Tiffany Lin <tiffany.lin@...iatek.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>

> diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> new file mode 100644
> index 0000000..f54fd89
> --- /dev/null
> +++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> @@ -0,0 +1,994 @@

<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