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X-MS-Exchange-CrossPremises-processed-by-journaling: Journal Agent X-OrganizationHeadersPreserved: BL0PR07MB5521.namprd07.prod.outlook.com Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org > -----Original Message----- > From: Alexandre Belloni > Sent: Friday, June 14, 2019 4:33 PM > To: Ken Sloat > Cc: Guenter Roeck ; nicolas.ferre@microchip.com; > ludovic.desroches@microchip.com; wim@linux-watchdog.org; linux-arm- > kernel@lists.infradead.org; linux-watchdog@vger.kernel.org; linux- > kernel@vger.kernel.org > Subject: Re: [PATCH v2 1/1] watchdog: atmel: atmel-sama5d4-wdt: Disable > watchdog on system suspend >=20 > [This is an EXTERNAL EMAIL] > ________________________________ >=20 > On 14/06/2019 18:43:22+0000, Ken Sloat wrote: > > Well I'm a little confused still because there are two separate > > comments in these statements. The first within resume implies that the > > init should be called because we might have lost register values for > > some reason unexplained. >=20 > The sama5d2 has a suspend mode where power to the core is completely > cut. Only a few IPs remain powered (in the backup power domain). > Unfortunately, the watchdog is not in that domain and may lose its regist= ers. >=20 > > Then within the init it says that the bootloader might have modified > > the registers so we should check them and then update it or otherwise > > disable it. I'm not trying to pick apart the logic or anything, I'm > > just readily assuming it is good as it was already reviewed before. > > >=20 > The bootloaders may have started the watchdog (this makes sense if you > really care about reliability) and so we need to be careful to keep the p= roper > parameters. Thanks for the explanation Alexandre I appreciate it. > > So without digging into that too much, if we don't know if any of the > > runtime situations above might have occurred, then isn't it best to > > leave my patch as is? Yes this has the side effect of resetting the > > timer count, but if the init call is needed and we don't have any way > > to know if any of the situations occurred, then we have no choice right= ? > > >=20 > Until we can differentiate between suspend modes, we have no other > choice. Ok I will leave my patch as is for now then > -- > Alexandre Belloni, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com Thanks, Ken Sloat