Messages in this thread | | | Subject | Re: [PATCH v10 5/5] Watchdog: ARM SBSA Generic Watchdog half timeout panic support | From | Guenter Roeck <> | Date | Sat, 6 Feb 2016 10:57:48 -0800 |
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On 02/06/2016 10:02 AM, Fu Wei wrote: > Hi Guenter, > > On 6 February 2016 at 07:54, Guenter Roeck <linux@roeck-us.net> wrote: >> On 02/05/2016 10:21 AM, Fu Wei wrote: >>> >>> On 5 February 2016 at 22:42, Guenter Roeck <linux@roeck-us.net> wrote: >>>> >>>> On 02/05/2016 01:51 AM, Fu Wei wrote: >>>>> >>>>> >>>>> Hi Guenter, >>>>> >>>>> On 4 February 2016 at 13:17, Guenter Roeck <linux@roeck-us.net> wrote: >>>>>> >>>>>> >>>>>> On 02/03/2016 03:00 PM, Fu Wei wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 4 February 2016 at 02:45, Timur Tabi <timur@codeaurora.org> wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Fu Wei wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> As you know I have made the pre-timeout support patch, If people >>>>>>>>> like >>>>>>>>> it, i am happy to go on upstream it separately. >>>>>>>>> >>>>>>>>> If we want to use pre-timeout here, user only can use get_pretimeout >>>>>>>>> and disable panic by setting pretimeout to 0 >>>>>>>>> but user can not really set pretimeout, because "pre-timeout == >>>>>>>>> timeout / 2 (always)". >>>>>>>>> if user want to change pretimeout, he/she has to set_time instead. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Ok, I think patches 4 and 5 should be combined, and I think the >>>>>>>> Kconfig >>>>>>>> entry should be removed and just use panic_enabled. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Agreed. >>>>> >>>>> >>>>> >>>>> np, will do >>>>> >>>>>>> >>>>>>> >>>>>>> NP, will update this patchset like that , thanks :-) >>>>>>> >>>>>> >>>>>> Also, if panic is enabled, the timeout needs to be adjusted accordingly >>>>>> (to only panic after the entire timeout period has expired, not after >>>>>> half of it). We can not panic the system after timeout / 2. >>>>> >>>>> >>>>> >>>>> OK, my thought is >>>>> >>>>> if panic is enabled : >>>>> |--------WOR-------WS0--------WOR-------WS1 >>>>> |------timeout------(panic)------timeout-----reset >>>>> >>>>> if panic is disabled . >>>>> |--------WOR-------WS0--------WOR-------WS1 >>>>> |---------------------timeout---------------------reset >>>>> >>>>> panic_enabled only can be configured when module is loaded by module >>>>> parameter >>>>> >>>>> But user should know that max_timeout(panic_enable) = >>>>> max_timeout(panic_disable) / 2 >>>>> >>>> >>>> That means you'll have to update max_timeout accordingly. >>> >>> >>> panic_enabled only can be configured when module is loaded, so we >>> don't need to update it. >>> >>> max_timeout will only be set up in the init stage. >>> >>> Does it make sense ? :-) >>> >> Not sure I understand your problem or question. >> >> max_timeout will have to reflect the correct maximum timeout, under >> all circumstances. It will have to be set to the correct value before >> the watchdog driver is registered. > > yes, understood, my thought is : > > in static int sbsa_gwdt_probe(struct platform_device *pdev) > > if (action) { > wdd->min_timeout = 1; > wdd->max_timeout = U32_MAX / gwdt->clk; > } else { > wdd->min_timeout = 2; > wdd->max_timeout = U32_MAX / gwdt->clk * 2;
Pretty much, though you would also have to adjust all calculations using gwdt->clk, in both set_timeout() and get_timeout(). Wonder if you could adjust gwdt->clk instead.
Does min_timeout really have to be 2 if panic is disabled ? The only reason seems to be the calculation in sbsa_gwdt_set_timeout().
writel(timeout / 2 * gwdt->clk, gwdt->control_base + SBSA_GWDT_WOR);
Maybe you could use something like
writel(timeout * (gwdt->clk / 2), ...);
instead. Or, as mentioned above, adjust the value of gwdt->clk to include the factor.
Thanks, Guenter
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