linux-kernel - Re: [PATCH v5,8/8] media: mediatek: vcodec: Add dbgfs help function

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Message-ID: <da165529-ae9a-8461-c582-9c85e6f2fa4c@xs4all.nl>
Date:   Tue, 30 May 2023 12:33:11 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Yunfei Dong <yunfei.dong@...iatek.com>,
        Chen-Yu Tsai <wenst@...omium.org>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, Nathan Hebert <nhebert@...omium.org>
Cc:     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 v5,8/8] media: mediatek: vcodec: Add dbgfs help function

On 5/30/23 12:06, AngeloGioacchino Del Regno wrote:
> Il 25/05/23 04:12, Yunfei Dong ha scritto:
>> Getting dbgfs help information with command "echo -help > vdec".
>>
>> Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
>> ---
>>   .../mediatek/vcodec/mtk_vcodec_dbgfs.c        | 24 ++++++++++++++++++-
>>   1 file changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
>> index 237d0dc8a1fc..2372fc449b45 100644
>> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
>> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dbgfs.c
>> @@ -52,6 +52,23 @@ static void mtk_vdec_dbgfs_get_format_type(struct mtk_vcodec_ctx *ctx, char *buf
>>   	*used += curr_len;
>>   }
>>   
>> +static void mtk_vdec_dbgfs_get_help(char *buf, int *used, int total)
>> +{
>> +	int curr_len;
>> +
>> +	curr_len = snprintf(buf + *used, total - *used,
>> +			    "help: (1: echo -'info' > vdec 2: cat vdec)\n");
>> +	*used += curr_len;
>> +
>> +	curr_len = snprintf(buf + *used, total - *used,
>> +			    "\t-picinfo: get resolution\n");
>> +	*used += curr_len;
>> +
>> +	curr_len = snprintf(buf + *used, total - *used,
>> +			    "\t-format: get output & capture queue format\n");
>> +	*used += curr_len;
>> +}
>> +
>>   static ssize_t mtk_vdec_dbgfs_write(struct file *filp, const char __user *ubuf,
>>   				    size_t count, loff_t *ppos)
>>   {
>> @@ -84,6 +101,11 @@ static ssize_t mtk_vdec_dbgfs_read(struct file *filp, char __user *ubuf,
>>   	if (!buf)
>>   		return -ENOMEM;
>>   
>> +	if (strstr(dbgfs->dbgfs_buf, "-help")) {
> 
> I would print the help strings in two conditions:
> 1. -help
> 2. (nothing)
> 
> ...so that if you don't echo anything to vdec (no params), you get the help text.
> Otherwise, you would have to know that "-help" is a parameter that gives you help
> text in the first place.
> 
> As for this commit "as is", it works as intended and it is useful to retrieve
> the help text; you can either send a followup commit that extends the help to
> the corner case that I've explained, or send a v6 adding that to this same commit.
> 
> I would prefer to see a v6 -- BUT -- since this series was sent a long time ago,
> you will get my R-b and I will leave the final choice to Hans.
> 
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> 
> 

I prefer a v6, rebased on top of the media_stage tree.

Regards,

	Hans