Messages in this thread | | | Subject | Re: [char-misc-next, v4, 5/7] watchdog: mei_wdt: register wd device only if required | From | Guenter Roeck <> | Date | Sun, 17 Jan 2016 13:47:21 -0800 |
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On 01/17/2016 12:54 PM, Winkler, Tomas wrote: > > >> -----Original Message----- >> From: Guenter Roeck [mailto:linux@roeck-us.net] >> Sent: Sunday, January 17, 2016 19:13 >> To: Winkler, Tomas >> Cc: Greg Kroah-Hartman; Wim Van Sebroeck; Usyskin, Alexander; linux- >> watchdog@vger.kernel.org; linux-kernel@vger.kernel.org >> Subject: Re: [char-misc-next, v4, 5/7] watchdog: mei_wdt: register wd device only >> if required >> >> Hi Tomas, >> >> On Fri, Jan 08, 2016 at 12:49:25AM +0200, Winkler, Tomas wrote: >>> From: Alexander Usyskin <alexander.usyskin@intel.com> >>> >>> For Intel Broadwell and newer platforms, the ME device can inform >>> the host whether the watchdog functionality is activated or not. >>> If the watchdog functionality is not activated then the watchdog interface >>> can be not registered and eliminate unnecessary pings and hence lower the >>> power consumption by avoiding waking up the device. >>> The feature can be deactivated also without reboot >>> in that case the watchdog device should be unregistered at runtime. >>> >>> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com> >>> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> >>> --- >>> V2: rework unregistration >>> V3: rebase; implement unregistraion also at runtime >>> V4: Rebase the code over patchset : "watchdog: Replace driver based >> refcounting" >>> >>> drivers/watchdog/mei_wdt.c | 196 >> ++++++++++++++++++++++++++++++++++++++++++--- >>> 1 file changed, 187 insertions(+), 9 deletions(-) >>> >>> diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c >>> index e7e3f144f2b0..85b27fc5d4ec 100644 >>> --- a/drivers/watchdog/mei_wdt.c >>> +++ b/drivers/watchdog/mei_wdt.c >>> >> [ ... ] >> >>> +static void mei_wdt_unregister_work(struct work_struct *work) >>> +{ >>> + struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister); >>> + >>> + mei_wdt_unregister(wdt); >>> +} >> >> Registration is synchronous, unregistration is asynchronous. >> >> Assuming that is on purpose, I think it warrants an explanation. >> > The unregistration is detected on response from the ping, which is run under same mutex as unregistration. > Tomas > > And that explains why registration can be synchronous and unregistration has to be asynchronous ?
Guenter
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