linux-kernel - Re: [PATCH] Revert "[media] au0828: use v4l2_mc_create_media

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Date:	Thu, 10 Mar 2016 09:16:30 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	mchehab@....samsung.com, hans.verkuil@...co.com,
	nenggun.kim@...sung.com, inki.dae@...sung.com,
	jh1009.sung@...sung.com, chehabrafael@...il.com,
	sakari.ailus@...ux.intel.com
Cc:	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH] Revert "[media] au0828: use v4l2_mc_create_media_graph()"

On 03/08/2016 08:26 PM, Shuah Khan wrote:
> This reverts commit 9822f4173f84cb7c592edb5e1478b7903f69d018.
> This commit breaks au0828_enable_handler() logic to find the tuner.
> Audio, Video, and Digital applications are broken and fail to start
> streaming with tuner busy error even when tuner is free.
> 
> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> ---
>  drivers/media/usb/au0828/au0828-video.c | 103 ++++++++++++++++++++++++++++++--
>  drivers/media/v4l2-core/v4l2-mc.c       |  21 +------
>  2 files changed, 99 insertions(+), 25 deletions(-)
> 

Hi Mauro,

Please pull this revert in as soon as possible. Without
the revert, auido, video, and digital applications won't
start even. There is a bug in the common routine introduced
in the commit 9822f4173f84cb7c592edb5e1478b7903f69d018 which
causes the link between source and sink to be not found.
I am testing on WIn-TV HVR 950Q

Here is my test sequence I use to verify the mutual exclusion
works between audio, video, and dvb applications.

Generate media graph graph - verify graph looks good.

Basic testing:
Test case 1:
Step 1: Start arecord and generate graph to verify the right
source is enabled
Step 2: Exit arecord and generate graph and verify resource is released.

Test case 2:
Step 1: Start kaffeine and generate graph to verify the right
source is enabled
Step 2: Exit kaffeine - generate graph and verify resource is released.

Test case 3:
Step 1: Start xawtv and generate graph to verify the right
source is enabled
Step 2: Exit xawtv - generate graph and verify resource is released.

Mutual exclusion testing:
Test case 1:
Step 1: Start arecord and generate graph to verify the right
source is enabled
Step 2: Start kaffeine - should see it fail to EBUSY
Step 3: Start xawtv - should see it fail with EBUSY
Step 4: Exit arecord - generate graph and verify resource is released.

Test Case 2:
Step 1: Start kaffeine and generate graph to verify the right
source is enabled
Step 2: Start arecord - it should fail - unable to set hwparams - device busy error
Step 3: Start xawtv - should see it fail with EBUSY
Step 4: Exit kaffeine - generate graph and verify resource is released.

Test Case 3:
Step 1: Start xawtv and generate graph to verify the right
source is enabled
Step 2: Start arecord - it should fail - device busy error
Step 3: Start kaffeine should see it fail with EBUSY
Step 4: Exit xawtv - generate graph and verify resource is released.

At each step make dmesg looks good. I build my kernel with kasan
enabled - to detect out of bounds access etc. good stuff.

thanks,
-- Shuah

-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@....samsung.com | (970) 217-8978