netdev - RE: [PATCH V1 net-next 0/3] net: stmmac: implement clocks

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Message-ID: <DB8PR04MB6795925488C63791C2BD588EE69F9@DB8PR04MB6795.eurprd04.prod.outlook.com>
Date:   Wed, 24 Feb 2021 01:45:40 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     "peppe.cavallaro@...com" <peppe.cavallaro@...com>,
        "alexandre.torgue@...com" <alexandre.torgue@...com>,
        "joabreu@...opsys.com" <joabreu@...opsys.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V1 net-next 0/3] net: stmmac: implement clocks


> -----Original Message-----
> From: Jakub Kicinski <kuba@...nel.org>
> Sent: 2021年2月24日 0:45
> To: Joakim Zhang <qiangqing.zhang@....com>
> Cc: peppe.cavallaro@...com; alexandre.torgue@...com;
> joabreu@...opsys.com; davem@...emloft.net; netdev@...r.kernel.org;
> dl-linux-imx <linux-imx@....com>
> Subject: Re: [PATCH V1 net-next 0/3] net: stmmac: implement clocks
> 
> On Tue, 23 Feb 2021 18:48:15 +0800 Joakim Zhang wrote:
> > In stmmac driver, clocks are all enabled after device probed, this
> > leads to more power consumption. This patch set tries to implement
> > clocks management, and takes i.MX platform as a example.

Hi Jakub,

Thanks for your kindly review!

> net-next is closed now and this is an optimization so please post as RFC until
> net-next is open again (see the note at the end of the email).

Ok, I will post as RFC during net-next on closed state.

> I'm not an expert on this stuff, but is there a reason you're not integrating this
> functionality with the power management subsystem?

Do you mean that implement runtime power management for driver? If yes, I think that is another feature, we can support later.

> I don't think it'd change the functionality, but it'd feel more idiomatic to fit in
> the standard Linux framework.

Yes, there is no functionality change, this patch set just adds clocks management.
In the driver now, we manage clocks at two point side:
1. enable clocks when probe driver, disable clocks when remove driver.
2. disable clocks when system suspend, enable clocks when system resume back.

This should not be enough, such as, even we close the NIC, the clocks still enabled. So this patch improve below:
Keep clocks disabled after driver probe, enable clocks when NIC up, and then disable clocks when NIC down.
The aim is to enable clocks when it needs, others keep clocks disabled.

Best Regards,
Joakim Zhang
> 
> 
> # Form letter - net-next is closed
> 
> We have already sent the networking pull request for 5.12 and therefore
> net-next is closed for new drivers, features, code refactoring and optimizations.
> We are currently accepting bug fixes only.
> 
> Please repost when net-next reopens after 5.12-rc1 is cut.
> 
> Look out for the announcement on the mailing list or check:
> https://eur01.safelinks.protection.outlook.com/?url=http:%2F%2Fvger.kernel.
> org%2F~davem%2Fnet-next.html&amp;data=04%7C01%7Cqiangqing.zhang%4
> 0nxp.com%7Ccfebfd0aac2b43ba9c9308d8d81a6194%7C686ea1d3bc2b4c6fa92
> cd99c5c301635%7C0%7C0%7C637496955136816595%7CUnknown%7CTWFpb
> GZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
> Mn0%3D%7C1000&amp;sdata=LLqX9utaTfnV5BV4JW6zoY76YzQiOe9Xlah58B
> 9jv1Y%3D&amp;reserved=0
> 
> RFC patches sent for review only are obviously welcome at any time.