From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from unicorn.mansr.com ([81.2.72.234]:60266 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751630AbbAKMpK convert rfc822-to-8bit (ORCPT ); Sun, 11 Jan 2015 07:45:10 -0500 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Lars-Peter Clausen Cc: Guenter Roeck , Ralf Baechle , Wim Van Sebroeck , Paul Burton , Paul Cercueil , Maarten ter Huurne , linux-mips@linux-mips.org, linux-watchdog@vger.kernel.org Subject: Re: [PATCH 1/3] MIPS: Use do_kernel_restart() as the default restart handler References: <1420914550-18335-1-git-send-email-lars@metafoo.de> <54B1CF9B.3060606@roeck-us.net> <54B26BB4.50707@metafoo.de> <54B26F5C.8050202@metafoo.de> Date: Sun, 11 Jan 2015 12:45:08 +0000 In-Reply-To: <54B26F5C.8050202@metafoo.de> (Lars-Peter Clausen's message of "Sun, 11 Jan 2015 13:41:00 +0100") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org Lars-Peter Clausen writes: > On 01/11/2015 01:30 PM, Måns Rullgård wrote: >> Lars-Peter Clausen writes: >> >>> On 01/11/2015 01:15 PM, Måns Rullgård wrote: >>>> Guenter Roeck writes: >>>> >>>>> On 01/10/2015 12:08 PM, Måns Rullgård wrote: >>>>>> Lars-Peter Clausen writes: >>>>>> >>>>>>> Use the recently introduced do_kernel_restart() function as the default restart >>>>>>> handler if the platform did not explicitly provide a restart handler. This >>>>>>> allows use restart handler that have been registered by device drivers to >>>>>>> restart the machine. >>>>>>> >>>>>>> Signed-off-by: Lars-Peter Clausen >>>>>>> --- >>>>>>> arch/mips/kernel/reset.c | 2 +- >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/arch/mips/kernel/reset.c b/arch/mips/kernel/reset.c >>>>>>> index 07fc524..36cd80c 100644 >>>>>>> --- a/arch/mips/kernel/reset.c >>>>>>> +++ b/arch/mips/kernel/reset.c >>>>>>> @@ -19,7 +19,7 @@ >>>>>>> * So handle all using function pointers to machine specific >>>>>>> * functions. >>>>>>> */ >>>>>>> -void (*_machine_restart)(char *command); >>>>>>> +void (*_machine_restart)(char *command) = do_kernel_restart; >>>>>>> void (*_machine_halt)(void); >>>>>>> void (*pm_power_off)(void); >>>>>> >>>>>> There is already a similar patch posted by Kevin Cernekee: >>>>>> http://www.linux-mips.org/archives/linux-mips/2014-12/msg00410.html >>>>>> >>>>> Personally I prefer the earlier patch, though I guess that is personal >>>>> preference. >>>> >>>> They both achieve the same thing, though Kevin's is more in line with >>>> what ARM does. Missing from both is a fallback while(1) loop in case no >>>> restart handlers are registered. With the restart moved to the watchdog >>>> driver, there's a possibility that this might happen. >>>> >>> >>> In my opinion if such a fallback is needed it should be put into the >>> kernel core reboot implementation and not into individual restart >>> handler implementations. >>> >>> My first version of this patch was do_kernel_restart() followed by a >>> machine_halt() (so it goes to sleep instead of busy looping) as a >>> fallback. But I couldn't find a good reason why that should be done at >>> the individual restart handler level, so I dropped it. >> >> ARM does it its arch machine_restart() function. MIPS should probably >> follow suit. >> > > That's just cargo culting... True. > Either it is required, then it should probably be moved into the core > kernel, or it is not required in which case it can be removed from the > ARM machine_restart() implementation. The quickest way to find out is probably to send a patch adding such code to the end of kernel_restart(). -- Måns Rullgård mans@mansr.com