linux-kernel - RE: [PATCH] can: flexcan: Implement CAN Runtime PM

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Date:   Tue, 27 Nov 2018 08:07:43 +0000
From:   Aisheng DONG <aisheng.dong@....com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>,
        Joakim Zhang <qiangqing.zhang@....com>,
        "wg@...ndegger.com" <wg@...ndegger.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH] can: flexcan: Implement CAN Runtime PM

> -----Original Message-----
> From: Marc Kleine-Budde [mailto:mkl@...gutronix.de]
> Sent: Tuesday, November 27, 2018 3:52 PM
> To: Joakim Zhang <qiangqing.zhang@....com>; wg@...ndegger.com;
> davem@...emloft.net
> Cc: linux-can@...r.kernel.org; netdev@...r.kernel.org;
> linux-kernel@...r.kernel.org; dl-linux-imx <linux-imx@....com>; Aisheng
> DONG <aisheng.dong@....com>
> Subject: Re: [PATCH] can: flexcan: Implement CAN Runtime PM
> 
> On 11/27/18 8:44 AM, Joakim Zhang wrote:
> >>> Flexcan will be disabled during suspend if no wakeup function
> >>> required and enabled after resume accordingly. During this period,
> >>> we could explicitly disable clocks.
> >>>
> >>> Implement Runtime PM which will:
> >>> 1) Keep device in suspend state (clocks disabled) if it's not
> >>> openned
> >>> 2) Make Power Domain framework be able to shutdown the corresponding
> >>> power domain of this device.
> >>
> >> Without CONFIG_PM the device fails to probe:
> >>
> >>> [  214.420606] flexcan 2090000.flexcan: 2090000.flexcan supply
> >>> xceiver not found, using dummy regulator [  214.445952] flexcan
> >>> 2090000.flexcan: Linked as a consumer to regulator.0 [  214.453448]
> >>> flexcan 2090000.flexcan: registering netdev failed [  214.459666]
> >>> flexcan 2090000.flexcan: Dropping the link to regulator.0 [
> >>> 214.472066] flexcan: probe of 2090000.flexcan failed with error -110
> 
> > I would sent V2 rebased on patch "can: flexcan: add self wakeup
> > support", and runtime pm works normally on MX6SX-SDB and MX7D-SDB.
> > So, could you tell me which board you tested on that causes the device
> > probe failed?
> 
> I tested on an imx6dl riotboard
> (https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Felixir.
> bootlin.com%2Flinux%2Flatest%2Fsource%2Farch%2Farm%2Fboot%2Fdts%2Fi
> mx6dl-riotboard.dts&amp;data=02%7C01%7Caisheng.dong%40nxp.com%7C8
> 4cfd3f3a08b4c7953fd08d6543d42c1%7C686ea1d3bc2b4c6fa92cd99c5c3016
> 35%7C0%7C0%7C636789019420569534&amp;sdata=rugKpmVaNn0ajTdctyi%
> 2F%2Bnwr%2FqqIBcikAP7eXLp6fcA%3D&amp;reserved=0
> + patches to enable CAN1) with an external PHY.
> 
> > And that CONFIG_PM has set in imx_v6_v7_defconfig which config file I
> used.
> 
> I disabled CONFIG_PM on purpose.

Joakim,
You need run the same test as Marc.

I guess It might because without CONFIG_PM, Runtime PM API
Simply return positive but the clock may still not enabled, thus cause
a CAN enable timeout.

You can check it.

Regards
Dong Aisheng

> 
> Marc
> 
> --
> Pengutronix e.K.                  | Marc Kleine-Budde           |
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