linux-kernel - Re: [PATCH 3/6 RESEND] media: mediatek: vcodec: Add a debugfs file to get different useful information

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Message-ID: <100a6c2e-f65f-5297-919a-06b8f73444fa@collabora.com>
Date:   Mon, 20 Mar 2023 15:49:36 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Yunfei Dong <yunfei.dong@...iatek.com>,
        Chen-Yu Tsai <wenst@...omium.org>,
        Nicolas Dufresne <nicolas@...fresne.ca>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Fritz Koenig <frkoenig@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Steve Cho <stevecho@...omium.org>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH 3/6 RESEND] media: mediatek: vcodec: Add a debugfs file to
 get different useful information

Il 20/03/23 11:28, Yunfei Dong ha scritto:
> In oder to get each instance information according to test command, adding
> one file node "vdec".
> 
> Can use echo command to set different string value as 'echo -picinfo > vdec'
> to get real and aligned resolution.
> 
> Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
> ---
>   .../mediatek/vcodec/mtk_vcodec_dbgfs.c        | 85 +++++++++++++++++++
>   .../mediatek/vcodec/mtk_vcodec_dbgfs.h        | 20 +++++
>   .../mediatek/vcodec/mtk_vcodec_dec_drv.c      |  2 +
>   3 files changed, 107 insertions(+)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> index bef78c028a75..9e7d57d21cea 100644
> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
> @@ -10,6 +10,86 @@
>   #include "mtk_vcodec_drv.h"
>   #include "mtk_vcodec_util.h"
>   
> +static ssize_t mtk_vdec_dbgfs_write(struct file *filp, const char __user *ubuf,
> +				    size_t count, loff_t *ppos)
> +{
> +	struct mtk_vcodec_dev *vcodec_dev = filp->private_data;
> +	char buf[32] = { 0 };
> +	int len, str_count = 0;
> +	struct mtk_vcodec_dbgfs_inst *dbgfs_inst;
> +	struct mtk_vcodec_ctx *ctx;
> +
> +	len = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, ubuf, count);
> +	if (len <= 0)
> +		return len;
> +
> +	list_for_each_entry(dbgfs_inst, &vcodec_dev->dbgfs.dbgfs_head, node) {
> +		pr_info("dbgfs_inst id: %d\n", dbgfs_inst->inst_id);
> +		ctx = dbgfs_inst->vcodec_ctx;
> +
> +		if (strstr(buf, "-picinfo")) {
> +			str_count++;
> +			pr_info("resolution: real(%dx%d)=>align(%dx%d)\n",
> +				ctx->picinfo.pic_w, ctx->picinfo.pic_h,
> +				ctx->picinfo.buf_w, ctx->picinfo.buf_h);

If you want to use debugfs (which is a good choice!), you should use debugfs!
This means that you shouldn't print this kind of information to the kernel,
but rather to a debugfs entry.

Example:

$ echo "-picinfo" > vdec
$ cat vdec

resolution: real(1024x768)=>align(something)

This is the same for all of the commits of this series, so, please properly
use debugfs.


Regards,
Angelo