linux-kernel - Re: [PATCH] media: ipu-cio2: Remove unnecessary runtime PM power state setting

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Date: Thu, 4 Apr 2024 07:27:47 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Yong Zhi <yong.zhi@...el.com>, Bingbu Cao <bingbu.cao@...el.com>,
	Dan Scally <djrscally@...il.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Tianshu Qiu <tian.shu.qiu@...el.com>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	Hyungwoo Yang <hyungwoo.yang@...el.com>,
	Rajmohan Mani <rajmohan.mani@...el.com>,
	Vijaykumar Ramya <ramya.vijaykumar@...el.com>,
	Samu Onkalo <samu.onkalo@...el.com>,
	Jouni Högander <jouni.hogander@...el.com>,
	Jouni Ukkonen <jouni.ukkonen@...el.com>,
	Antti Laakso <antti.laakso@...el.com>
Subject: Re: [PATCH] media: ipu-cio2: Remove unnecessary runtime PM power
 state setting

Hi Bjorn,

On Mon, Mar 25, 2024 at 05:03:25PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> ipu-cio2 uses generic power management, and pci_pm_runtime_suspend() and
> pci_pm_runtime_resume() already take care of setting the PCI device power
> state, so the driver doesn't need to do it explicitly.
> 
> Remove explicit setting to D3hot or D0 during runtime suspend and resume.
> 
> Remove #defines that are no longer used.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Hyungwoo Yang <hyungwoo.yang@...el.com>
> Cc: Rajmohan Mani <rajmohan.mani@...el.com>
> Cc: Vijaykumar Ramya <ramya.vijaykumar@...el.com>
> Cc: Samu Onkalo <samu.onkalo@...el.com>
> Cc: Jouni Högander <jouni.hogander@...el.com>
> Cc: Jouni Ukkonen <jouni.ukkonen@...el.com>
> Cc: Antti Laakso <antti.laakso@...el.com>
> ---
> This code was initially added by c2a6a07afe4a ("media: intel-ipu3: cio2:
> add new MIPI-CSI2 driver").
> 
> Even at that time, the explicit power state setting should not have been
> necessary, so maybe there's a reason for it.  I have no way to test this,
> so if it *is* needed, please:
> 
>   - Add a comment about the reason and
> 
>   - Convert it to use pci_set_power_state() so the PCI core knows about the
>     change and all the required state transition delays are observed.

Thanks for the patch.

The device seems to work fine with the patch applied so I presume it wasn't
necessary to begin with.

-- 
Regards,

Sakari Ailus