Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Robin Gong <yibin.gong@nxp.com>
To:     Guenter Roeck <linux@roeck-us.net>
CC:     "wim@linux-watchdog.org" <wim@linux-watchdog.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        dl-linux-imx <linux-imx@nxp.com>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v1] watchdog: imx2_wdt: clear WDOG_HW_RUNNING before
 suspend
Thread-Topic: [PATCH v1] watchdog: imx2_wdt: clear WDOG_HW_RUNNING before
 suspend
Thread-Index: AQHXRhJF8Us7ySGmV06kW0fPHW7nEqrdp+uAgAIKKQCAADQMgIAA4GQg
Date:   Thu, 13 May 2021 03:49:23 +0000
Message-ID: <VE1PR04MB6688A83899254F38221CE02A89519@VE1PR04MB6688.eurprd04.prod.outlook.com>
References: <1620732032-7675-1-git-send-email-yibin.gong@nxp.com>
 <d5364293-8cba-0d39-aa45-a55c5d6d2af6@roeck-us.net>
 <VE1PR04MB66889A576AD92D4D789199D489529@VE1PR04MB6688.eurprd04.prod.outlook.com>
 <20210512141435.GL1333995@roeck-us.net>
In-Reply-To: <20210512141435.GL1333995@roeck-us.net>
Accept-Language: en-US
Content-Language: en-US
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: bb9ae2f4-c92c-4695-930a-08d915c218f6
X-MS-Exchange-CrossTenant-originalarrivaltime: 13 May 2021 03:49:23.4948
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: 54wdolHl1iMAnM7Rln2obQcQ2pAPIWVQqU4kVtu7Tojmoo/X+WER56QBUT2WWAFCN5xBdLYseI6O4x7mQtwdmw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR04MB6286
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 5/12/21 22:15 Guenter Roeck <groeck7@gmail.com> wrote:
> We can not assume that the situation is exactly the same for all drivers =
and
> use a core flag to indicate some driver specific state just to avoid a
> driver-internal flag.
>=20
> Either case, it looks like you are saying that the watchdog can be stoppe=
d after
> all, by disabling its clock.
>=20
> > BTW, for i.mx2_wdt which watchdog can't be stop unless kernel enter
> > into suspend, that seems like watchdog stop after suspend and clear
> > WDOG_HW_RUNNING makes sense?
> >
>=20
> Yes, if you make it official and add a stop function which disables the
> watchdog by stopping its clock. Then the driver should not set
> WDOG_HW_RUNNING in the first place, and use the normal mechanisms to
> start and stop the watchdog.
> That would include starting the clock in the start function, and stopping=
 it in
> the stop function.
>=20
Sorry, watchdog can't be stopped by disabling clock. The only way to stop w=
atchdog
is SOC enter Deep Sleep Mode(suspend) and stopped by HW,  so the suspend fl=
ow
looks like 'watchdog stop' which I though WDOG_HW_RUNNING makes sense.=20
Okay, I will use internal flag instead of WDOG_HW_RUNNING in v2, thanks.