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Message-ID: <e901967f-59df-f4b0-de51-61e542c04161@ti.com>
Date: Thu, 20 Jun 2024 19:50:14 +0530
From: Devarsh Thakkar <devarsht@...com>
To: Nicolas Dufresne <nicolas.dufresne@...labora.com>,
"jackson.lee"
<jackson.lee@...psnmedia.com>,
"mchehab@...nel.org" <mchehab@...nel.org>,
"sebastian.fricke@...labora.com" <sebastian.fricke@...labora.com>
CC: "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"hverkuil@...all.nl" <hverkuil@...all.nl>,
Nas Chung
<nas.chung@...psnmedia.com>,
"lafley.kim" <lafley.kim@...psnmedia.com>,
"b-brnich@...com" <b-brnich@...com>, "Luthra, Jai" <j-luthra@...com>,
Vibhore
<vibhore@...com>, Dhruva Gole <d-gole@...com>,
Aradhya <a-bhatia1@...com>, "Raghavendra, Vignesh" <vigneshr@...com>
Subject: Re: [RESEND PATCH v6 2/4] media: chips-media: wave5: Support runtime
suspend/resume
Hi Nicolas,
On 20/06/24 19:35, Nicolas Dufresne wrote:
> Hi Devarsh,
>
> Le jeudi 20 juin 2024 à 15:05 +0530, Devarsh Thakkar a écrit :
>> In my view the delayed suspend functionality is generally helpful for devices
>> where resume latencies are higher for e.g. this light sensor driver [2] uses
>> it because it takes 250ms to stabilize after resumption and I don't see this
>> being used in codec drivers generally since there is no such large resume
>> latency. Please let me know if I am missing something or there is a strong
>> reason to have delayed suspend for wave5.
>
> It sounds like you did proper scientific testing of the suspend results calls,
> mind sharing the actual data ?
Nopes, I did not do that but yes I agree it is good to profile and evaluate
the trade-off but I am not expecting 250ms kind of latency. I would suggest
Jackson to do the profiling for the resume latencies.
But perhaps a separate issue, I did notice that intention of the patchset was
to suspend without waiting for the timeout if there is no application having a
handle to the wave5 device but even if I close the last instance I still see
the IP stays on for 5seconds as seen in this logs [1] and this perhaps could
be because extra pm counter references being hold.
[2024-06-20 12:32:50] Freeing pipeline ...
and after 5 seconds..
[2024-06-20 12:32:55] | 204 | AM62AX_DEV_CODEC0 | DEVICE_STATE_ON |
[2024-06-20 12:32:56] | 204 | AM62AX_DEV_CODEC0 | DEVICE_STATE_OFF
[1]: https://gist.github.com/devarsht/009075d8706001f447733ed859152d90
Regards
Devarsh
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