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Subject: Re: [PATCH] staging: media: rkisp1: make links immutable by default
To:     =?UTF-8?Q?Niklas_S=c3=b6derlund?= <niklas.soderlund@ragnatech.se>
Cc:     linux-media@vger.kernel.org, hverkuil-cisco@xs4all.nl,
        kernel@collabora.com, laurent.pinchart@ideasonboard.com,
        tfiga@chromium.org, Mauro Carvalho Chehab <mchehab@kernel.org>,
        devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
References: <20200117201218.3745311-1-helen.koike@collabora.com>
 <20200117223634.GJ1074550@oden.dyn.berto.se>
From:   Helen Koike <helen.koike@collabora.com>
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Message-ID: <8011cc70-a32c-efe3-817d-6a17ae672fd4@collabora.com>
Date:   Sun, 19 Jan 2020 12:14:10 -0300
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On 1/17/20 8:36 PM, Niklas Söderlund wrote:
> Hi Helen,
> 
> Thanks for your work.
> 
> On 2020-01-17 17:12:18 -0300, Helen Koike wrote:
>> The only places which make sese to allow users to enable or disable
>> links are:
>>
>> * between sensors and isp:
>> So users can select which sensor should be used while streaming
>>
>> * between isp and the resizers:
>>               |
>>               v here
>> rkisp1_isp:2 -> rkisp1_resizer_mainpath -> rkisp1_mainpath (capture)
>>             \-> rkisp1_resizer_selfpath -> rkisp1_selfpath (capture)
>>               ^ here
>>               |
>>
>> So users can disable one of the capture paths when unused, to avoid
>> worring about matching formats.
>>
>> Make the following links immutable to simplify userspace:
>>
>> rkisp1_resizer_mainpath -> rkisp1_mainpath
>> rkisp1_resizer_selfpath -> rkisp1_selfpath
>> rkisp1_params           -> rkisp1_isp
>> rkisp1_isp              -> rkisp1_stats
>>
>> Signed-off-by: Helen Koike <helen.koike@collabora.com>
>>
>> ---
>> This is the topology graph after disabling all the links with
>> media -r
>> http://col.la/rkisp1immutable
>>
>> Dashed links are the only one can can be enabled/disabled, the others
>> are immutable.
>>
>>  drivers/staging/media/rkisp1/rkisp1-dev.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/media/rkisp1/rkisp1-dev.c b/drivers/staging/media/rkisp1/rkisp1-dev.c
>> index 558126e66465..4030d5e71af1 100644
>> --- a/drivers/staging/media/rkisp1/rkisp1-dev.c
>> +++ b/drivers/staging/media/rkisp1/rkisp1-dev.c
>> @@ -145,14 +145,15 @@ static int rkisp1_create_links(struct rkisp1_device *rkisp1)
>>  		flags = 0;
>>  	}
>>  
>> -	flags = MEDIA_LNK_FL_ENABLED;
>> +	flags = MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE;
>>  
>>  	/* create ISP->RSZ->CAP links */
>>  	for (i = 0; i < 2; i++) {
>>  		source = &rkisp1->isp.sd.entity;
>>  		sink = &rkisp1->resizer_devs[i].sd.entity;
> 
> nit: To keep with the style of the rest of the function I would set 
> flags here and once more bellow in the same loop.


Do you mean this: http://ix.io/27Pm ?
hmm, I don't see why to assign flags inside the loop.
the previous loop is a different case, since it sets the link
to the first sensor as enabled, but the other sensor links are disabled
(in case there are more then one link).

> 
> With or without this fixed,
> 
> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

Thanks,
Helen

> 
>>  		ret = media_create_pad_link(source, RKISP1_ISP_PAD_SOURCE_VIDEO,
>> -					    sink, RKISP1_RSZ_PAD_SINK, flags);
>> +					    sink, RKISP1_RSZ_PAD_SINK,
>> +					    MEDIA_LNK_FL_ENABLED);
>>  		if (ret)
>>  			return ret;
>>  
>> -- 
>> 2.24.0
>>
>