[PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Quanxian Wang]

According to the bspec, when set N/M, should disable
and enable transcoder which attaching DP audio. However
with that implementation will affect performance more.

But with current implementation, KBL could not work with defined N/M.
By default, KBL will use automatic N/M.

Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
Reviewed-by: Libin Yang <libin.yang@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/intel_audio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index d805b6e..ba4994e 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -289,6 +289,10 @@ hsw_dp_audio_config_update(struct intel_crtc *intel_crtc, enum port port,
 	enum pipe pipe = intel_crtc->pipe;
 	u32 tmp;
 
+	/* It doesn't work on KBL and uses automatic N/M. */
+	if (IS_KABYLAKE(dev_priv))
+		nm = NULL;
+
 	if (nm)
 		DRM_DEBUG_KMS("using Maud %u, Naud %u\n", nm->m, nm->n);
 	else
-- 
2.5.0

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✓ Fi.CI.BAT: success for Defined NM doesn't work on KBL and uses automatic N/M.

[Patchwork]

== Series Details ==

Series: Defined NM doesn't work on KBL and uses automatic N/M.
URL   : https://patchwork.freedesktop.org/series/24938/
State : success

== Summary ==

Series 24938v1 Defined NM doesn't work on KBL and uses automatic N/M.
https://patchwork.freedesktop.org/api/1.0/series/24938/revisions/1/mbox/

fi-bdw-5557u     total:278  pass:267  dwarn:0   dfail:0   fail:0   skip:11  time:446s
fi-bdw-gvtdvm    total:278  pass:256  dwarn:8   dfail:0   fail:0   skip:14  time:428s
fi-bsw-n3050     total:278  pass:242  dwarn:0   dfail:0   fail:0   skip:36  time:579s
fi-bxt-j4205     total:278  pass:259  dwarn:0   dfail:0   fail:0   skip:19  time:513s
fi-byt-j1900     total:278  pass:254  dwarn:0   dfail:0   fail:0   skip:24  time:485s
fi-byt-n2820     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:484s
fi-hsw-4770      total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:421s
fi-hsw-4770r     total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:410s
fi-ilk-650       total:278  pass:228  dwarn:0   dfail:0   fail:0   skip:50  time:418s
fi-ivb-3520m     total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:484s
fi-ivb-3770      total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:468s
fi-kbl-7500u     total:278  pass:255  dwarn:5   dfail:0   fail:0   skip:18  time:462s
fi-kbl-7560u     total:278  pass:263  dwarn:5   dfail:0   fail:0   skip:10  time:570s
fi-skl-6260u     total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:462s
fi-skl-6700hq    total:278  pass:239  dwarn:0   dfail:1   fail:17  skip:21  time:438s
fi-skl-6700k     total:278  pass:256  dwarn:4   dfail:0   fail:0   skip:18  time:464s
fi-skl-6770hq    total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:499s
fi-skl-gvtdvm    total:278  pass:265  dwarn:0   dfail:0   fail:0   skip:13  time:440s
fi-snb-2520m     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:541s
fi-snb-2600      total:278  pass:249  dwarn:0   dfail:0   fail:0   skip:29  time:398s

d47b71fd942d8a88da311863a6cfc2fd73ba1234 drm-tip: 2017y-05m-25d-20h-54m-23s UTC integration manifest
3784560 Defined NM doesn't work on KBL and uses automatic N/M.

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4815/
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Jani Nikula]

On Fri, 26 May 2017, Quanxian Wang <quanxian.wang@intel.com> wrote:
> According to the bspec, when set N/M, should disable
> and enable transcoder which attaching DP audio. However
> with that implementation will affect performance more.
>
> But with current implementation, KBL could not work with defined N/M.
> By default, KBL will use automatic N/M.
>
> Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
> Reviewed-by: Libin Yang <libin.yang@intel.com>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>

I have *NOT* reviewed this patch. Even if it's based on my suggestion in
[1], it does not automatically signify review.

The patch subject should start with "drm/i915/audio:".

The DP spec always expresses the values as M/N, more specifically
Maud/Naud, so it's confusing to see them expressed as N/M.

I still have trouble understanding the commit message. I am wondering if
something was fixed in Kabylake and beyond, since according to
6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset") we need this
for certain modes. In particular, should the condition check for KBL ||
gen >= 10?

BR,
Jani.


[1] http://mid.mail-archive.com/87pogs1lz7.fsf@intel.com



> ---
>  drivers/gpu/drm/i915/intel_audio.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> index d805b6e..ba4994e 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -289,6 +289,10 @@ hsw_dp_audio_config_update(struct intel_crtc *intel_crtc, enum port port,
>  	enum pipe pipe = intel_crtc->pipe;
>  	u32 tmp;
>  
> +	/* It doesn't work on KBL and uses automatic N/M. */
> +	if (IS_KABYLAKE(dev_priv))
> +		nm = NULL;
> +
>  	if (nm)
>  		DRM_DEBUG_KMS("using Maud %u, Naud %u\n", nm->m, nm->n);
>  	else

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Wang, Quanxian]

Hi, Jani

Thanks for your comment. My comment below.

-----Original Message-----
From: Jani Nikula [mailto:jani.nikula@linux.intel.com] 
Sent: Friday, May 26, 2017 4:31 PM
To: Wang, Quanxian <quanxian.wang@intel.com>; intel-gfx@lists.freedesktop.org
Cc: Yang, Libin <libin.yang@intel.com>; Wang, Quanxian <quanxian.wang@intel.com>
Subject: Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

On Fri, 26 May 2017, Quanxian Wang <quanxian.wang@intel.com> wrote:
> According to the bspec, when set N/M, should disable and enable 
> transcoder which attaching DP audio. However with that implementation 
> will affect performance more.
>
> But with current implementation, KBL could not work with defined N/M.
> By default, KBL will use automatic N/M.
>
> Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
> Reviewed-by: Libin Yang <libin.yang@intel.com>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>

I have *NOT* reviewed this patch. Even if it's based on my suggestion in [1], it does not automatically signify review.
[Wang, Quanxian] Sorry, I accept your suggestion. So in order to respect what you said, I input your name here.

The patch subject should start with "drm/i915/audio:".
[Wang, Quanxian] Ok.

The DP spec always expresses the values as M/N, more specifically Maud/Naud, so it's confusing to see them expressed as N/M.
[Wang, Quanxian] accept it.

I still have trouble understanding the commit message. I am wondering if something was fixed in Kabylake and beyond, since according to
[Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL and more, the audio doesn't work on KBL specially, and other platform works fine. Even if with latest upstream kernel, but it works on 4.8 kernel. Therefore It is a regression issue. After investigation, we found it is caused by  commit "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper N/M in modeset". Therefore I provided this patch.
After getting suggestion from you and Libin, we do more testing on 4K monitor for audio delay issue. Also talked with Libin why not use transcoder disable/enable process described in bspec, it will affect performance.
This is the whole story. You can check LCK number 3791 in Intel JIRA about that.

6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset") we need this for certain modes. In particular, should the condition check for KBL || gen >= 10?

[Wang, Quanxian] Basically if upstream could provide a reasonable patch, it will appreciate since you are expert in this area.
Thanks for your understanding.

BR,
Jani.


[1] http://mid.mail-archive.com/87pogs1lz7.fsf@intel.com



> ---
>  drivers/gpu/drm/i915/intel_audio.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_audio.c 
> b/drivers/gpu/drm/i915/intel_audio.c
> index d805b6e..ba4994e 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -289,6 +289,10 @@ hsw_dp_audio_config_update(struct intel_crtc *intel_crtc, enum port port,
>  	enum pipe pipe = intel_crtc->pipe;
>  	u32 tmp;
>  
> +	/* It doesn't work on KBL and uses automatic N/M. */
> +	if (IS_KABYLAKE(dev_priv))
> +		nm = NULL;
> +
>  	if (nm)
>  		DRM_DEBUG_KMS("using Maud %u, Naud %u\n", nm->m, nm->n);
>  	else

--
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Jani Nikula]

On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
> [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL
> and more, the audio doesn't work on KBL specially, and other platform
> works fine. Even if with latest upstream kernel, but it works on 4.8
> kernel. Therefore It is a regression issue. After investigation, we
> found it is caused by commit
> "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper
> N/M in modeset". Therefore I provided this patch.

If it's a regression, we need to backport the fix to stable kernels, and
the patch needs annotation:

Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
Cc: <stable@vger.kernel.org> # v4.10+

> After getting suggestion from you and Libin, we do more testing on 4K
> monitor for audio delay issue. Also talked with Libin why not use
> transcoder disable/enable process described in bspec, it will affect
> performance.
>
> This is the whole story. You can check LCK number 3791 in Intel JIRA
> about that.

Actually, I can't. And the commit message needs to have the
explanation. I still do not know what the bug is specifically, or why
Kabylake, and only Kabylake, needs this.

> [Wang, Quanxian] Basically if upstream could provide a reasonable
> patch, it will appreciate since you are expert in this area.
> Thanks for your understanding.

The patch is probably fine. But I can't invent an explanation if I don't
know what the problem is.


BR,
Jani.

-- 
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Wang, Quanxian]

"The patch is probably fine. But I can't invent an explanation if I don't know what the problem is."

@Jani @libin, is it possible for you to help contact Intel graphics hardware design engineer to get the reason why M/N doesn't work as you implemented in kernel code in Kabylake platform? I don't find good reason in bspec. Thanks.

-----Original Message-----
From: Jani Nikula [mailto:jani.nikula@linux.intel.com] 
Sent: Friday, May 26, 2017 7:01 PM
To: Wang, Quanxian <quanxian.wang@intel.com>; intel-gfx@lists.freedesktop.org
Cc: Yang, Libin <libin.yang@intel.com>
Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
> [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL 
> and more, the audio doesn't work on KBL specially, and other platform 
> works fine. Even if with latest upstream kernel, but it works on 4.8 
> kernel. Therefore It is a regression issue. After investigation, we 
> found it is caused by commit 
> "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper 
> N/M in modeset". Therefore I provided this patch.

If it's a regression, we need to backport the fix to stable kernels, and the patch needs annotation:

Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
Cc: <stable@vger.kernel.org> # v4.10+

> After getting suggestion from you and Libin, we do more testing on 4K 
> monitor for audio delay issue. Also talked with Libin why not use 
> transcoder disable/enable process described in bspec, it will affect 
> performance.
>
> This is the whole story. You can check LCK number 3791 in Intel JIRA 
> about that.

Actually, I can't. And the commit message needs to have the explanation. I still do not know what the bug is specifically, or why Kabylake, and only Kabylake, needs this.

> [Wang, Quanxian] Basically if upstream could provide a reasonable 
> patch, it will appreciate since you are expert in this area.
> Thanks for your understanding.

The patch is probably fine. But I can't invent an explanation if I don't know what the problem is.


BR,
Jani.

--
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Jani Nikula]

On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
> "The patch is probably fine. But I can't invent an explanation if I
> don't know what the problem is."
>
> @Jani @libin, is it possible for you to help contact Intel graphics
> hardware design engineer to get the reason why M/N doesn't work as you
> implemented in kernel code in Kabylake platform? I don't find good
> reason in bspec. Thanks.

How did you come up with the patch then? What made you try this?

BR,
Jani.


>
> -----Original Message-----
> From: Jani Nikula [mailto:jani.nikula@linux.intel.com] 
> Sent: Friday, May 26, 2017 7:01 PM
> To: Wang, Quanxian <quanxian.wang@intel.com>; intel-gfx@lists.freedesktop.org
> Cc: Yang, Libin <libin.yang@intel.com>
> Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.
>
> On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
>> [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL 
>> and more, the audio doesn't work on KBL specially, and other platform 
>> works fine. Even if with latest upstream kernel, but it works on 4.8 
>> kernel. Therefore It is a regression issue. After investigation, we 
>> found it is caused by commit 
>> "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper 
>> N/M in modeset". Therefore I provided this patch.
>
> If it's a regression, we need to backport the fix to stable kernels, and the patch needs annotation:
>
> Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
> Cc: <stable@vger.kernel.org> # v4.10+
>
>> After getting suggestion from you and Libin, we do more testing on 4K 
>> monitor for audio delay issue. Also talked with Libin why not use 
>> transcoder disable/enable process described in bspec, it will affect 
>> performance.
>>
>> This is the whole story. You can check LCK number 3791 in Intel JIRA 
>> about that.
>
> Actually, I can't. And the commit message needs to have the explanation. I still do not know what the bug is specifically, or why Kabylake, and only Kabylake, needs this.
>
>> [Wang, Quanxian] Basically if upstream could provide a reasonable 
>> patch, it will appreciate since you are expert in this area.
>> Thanks for your understanding.
>
> The patch is probably fine. But I can't invent an explanation if I don't know what the problem is.
>
>
> BR,
> Jani.
>
> --
> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center
_______________________________________________
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Wang, Quanxian]

-----Original Message-----
From: Jani Nikula [mailto:jani.nikula@linux.intel.com] 
Sent: Monday, May 29, 2017 4:29 PM
To: Wang, Quanxian <quanxian.wang@intel.com>; intel-gfx@lists.freedesktop.org
Cc: Yang, Libin <libin.yang@intel.com>
Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.


On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
> "The patch is probably fine. But I can't invent an explanation if I 
> don't know what the problem is."
>
> @Jani @libin, is it possible for you to help contact Intel graphics 
> hardware design engineer to get the reason why M/N doesn't work as you 
> implemented in kernel code in Kabylake platform? I don't find good 
> reason in bspec. Thanks.

How did you come up with the patch then? What made you try this?
[Wang, Quanxian] I am from OSV enabling team and responsible for Ubuntu enabling. 17.04 (kernel 4.10) is released, we will do full testing for all Intel platforms including KBL/SKL... With audio testing, we found this regression issue on KBL and find patch caused this regression. Compared with previous implementation, we use automatic M/N to have a try. It works. 

BR,
Jani.


>
> -----Original Message-----
> From: Jani Nikula [mailto:jani.nikula@linux.intel.com]
> Sent: Friday, May 26, 2017 7:01 PM
> To: Wang, Quanxian <quanxian.wang@intel.com>; 
> intel-gfx@lists.freedesktop.org
> Cc: Yang, Libin <libin.yang@intel.com>
> Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.
>
> On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
>> [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL 
>> and more, the audio doesn't work on KBL specially, and other platform 
>> works fine. Even if with latest upstream kernel, but it works on 4.8 
>> kernel. Therefore It is a regression issue. After investigation, we 
>> found it is caused by commit 
>> "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper 
>> N/M in modeset". Therefore I provided this patch.
>
> If it's a regression, we need to backport the fix to stable kernels, and the patch needs annotation:
>
> Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
> Cc: <stable@vger.kernel.org> # v4.10+
>
>> After getting suggestion from you and Libin, we do more testing on 4K 
>> monitor for audio delay issue. Also talked with Libin why not use 
>> transcoder disable/enable process described in bspec, it will affect 
>> performance.
>>
>> This is the whole story. You can check LCK number 3791 in Intel JIRA 
>> about that.
>
> Actually, I can't. And the commit message needs to have the explanation. I still do not know what the bug is specifically, or why Kabylake, and only Kabylake, needs this.
>
>> [Wang, Quanxian] Basically if upstream could provide a reasonable 
>> patch, it will appreciate since you are expert in this area.
>> Thanks for your understanding.
>
> The patch is probably fine. But I can't invent an explanation if I don't know what the problem is.
>
>
> BR,
> Jani.
>
> --
> Jani Nikula, Intel Open Source Technology Center

--
Jani Nikula, Intel Open Source Technology Center
_______________________________________________
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Re: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.

[Wang, Quanxian]

Hi, Jani

I have created a Bugzilla in free desktop for tracking.
https://bugs.freedesktop.org/show_bug.cgi?id=104093

Appreciate find audio expert could help us address root cause.

Thank you.

Quanxian

-----Original Message-----
From: Intel-gfx [mailto:intel-gfx-bounces@lists.freedesktop.org] On Behalf Of Wang, Quanxian
Sent: Wednesday, May 31, 2017 11:21 AM
To: Jani Nikula <jani.nikula@linux.intel.com>; intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.



-----Original Message-----
From: Jani Nikula [mailto:jani.nikula@linux.intel.com] 
Sent: Monday, May 29, 2017 4:29 PM
To: Wang, Quanxian <quanxian.wang@intel.com>; intel-gfx@lists.freedesktop.org
Cc: Yang, Libin <libin.yang@intel.com>
Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.


On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
> "The patch is probably fine. But I can't invent an explanation if I 
> don't know what the problem is."
>
> @Jani @libin, is it possible for you to help contact Intel graphics 
> hardware design engineer to get the reason why M/N doesn't work as you 
> implemented in kernel code in Kabylake platform? I don't find good 
> reason in bspec. Thanks.

How did you come up with the patch then? What made you try this?
[Wang, Quanxian] I am from OSV enabling team and responsible for Ubuntu enabling. 17.04 (kernel 4.10) is released, we will do full testing for all Intel platforms including KBL/SKL... With audio testing, we found this regression issue on KBL and find patch caused this regression. Compared with previous implementation, we use automatic M/N to have a try. It works. 

BR,
Jani.


>
> -----Original Message-----
> From: Jani Nikula [mailto:jani.nikula@linux.intel.com]
> Sent: Friday, May 26, 2017 7:01 PM
> To: Wang, Quanxian <quanxian.wang@intel.com>; 
> intel-gfx@lists.freedesktop.org
> Cc: Yang, Libin <libin.yang@intel.com>
> Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M.
>
> On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@intel.com> wrote:
>> [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL 
>> and more, the audio doesn't work on KBL specially, and other platform 
>> works fine. Even if with latest upstream kernel, but it works on 4.8 
>> kernel. Therefore It is a regression issue. After investigation, we 
>> found it is caused by commit 
>> "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper 
>> N/M in modeset". Therefore I provided this patch.
>
> If it's a regression, we need to backport the fix to stable kernels, and the patch needs annotation:
>
> Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset")
> Cc: <stable@vger.kernel.org> # v4.10+
>
>> After getting suggestion from you and Libin, we do more testing on 4K 
>> monitor for audio delay issue. Also talked with Libin why not use 
>> transcoder disable/enable process described in bspec, it will affect 
>> performance.
>>
>> This is the whole story. You can check LCK number 3791 in Intel JIRA 
>> about that.
>
> Actually, I can't. And the commit message needs to have the explanation. I still do not know what the bug is specifically, or why Kabylake, and only Kabylake, needs this.
>
>> [Wang, Quanxian] Basically if upstream could provide a reasonable 
>> patch, it will appreciate since you are expert in this area.
>> Thanks for your understanding.
>
> The patch is probably fine. But I can't invent an explanation if I don't know what the problem is.
>
>
> BR,
> Jani.
>
> --
> Jani Nikula, Intel Open Source Technology Center

--
Jani Nikula, Intel Open Source Technology Center
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