Hi Guenter, On 10 June 2015 at 23:38, Fu Wei <fu.wei@xxxxxxxxxx> wrote: > Hi Guenter, > > > On 10 June 2015 at 11:41, Fu Wei <fu.wei@xxxxxxxxxx> wrote: >> Hi Guenter, >> >> On 10 June 2015 at 00:45, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: >>> On 06/09/2015 09:29 AM, Timur Tabi wrote: >>>> >>>> On 06/09/2015 11:22 AM, Guenter Roeck wrote: >>>>> >>>>> >>>>> >>>>> but I see your point. Essentially, the specification is broken >>>>> for all practical purposes, since, as you point out, enabling >>>>> the watchdog overwrites and explicitly sets WCV. Effectively >>>>> this means that just using WCV to program the timeout period >>>>> is not really possible. >>>>> >>>>> I am not really sure how to address this. We can either only use WOR, >>>>> and forget about pretimeout, or we can enforce a minimum pretimeout. >>>>> In the latter case, we'll have to write WCV after writing WOR. >>>> >>>> >>>> In talking with our hardware engineers, using WCV to program the timeout >>>> period is not a valid operation. This is why I keep arguing against the >>>> pre-timeout feature, and I don't agree that servers should always use >>>> pre-timeout. >>>> >>> >>> Not sure if "not valid" is correct - after all, it is mentioned in the >>> specification. However, it is at the very least fragile. >> >> I think we should focus on SBSA spec, but not a specific chip design, >> because this is SBSA watchdog, not a driver for an IP core from a >> specific chip vendor. >> this operation is mentioned in the spec, >> and I have tested my driver on Foundation model(from ARM) and a real hardware. >> >>> >>> I tend to agree that we should just forget about pretimeout and >>> use your original approach, where the timeout value is used >>> to program WOR. Everything else is really just asking for trouble. >> >> I don't mind if we give up pretimeout, The reason I use pretimeout is: >> this concept matches the function of two stage timeouts. >> >> but, If we give up pretimeout, could you give me a suggestion: >> >> How to config the two stage timeouts >> (1)from enabling watchdog to WS0 >> (2)the time from WS1 to WS0 >> >> If we only have one timeout parameter, How to config the two stage timeouts? >> Any suggestion ? > > I have another thought for this, please allow me to sent anther > patchset in a day. see if you like it. I have sent a non-pretimeout version patchset, please let me know if you like the non-pretimeout version more. Great thanks for your time. :-) > >> >> If we make the first stage timeout is timeout/2, this violates the >> definition of timeout. >> I don't think users expect interrupt, panic or reboot at timeout/2. >> >> And WS1 definitely isn't a backup of WS0. >> >>> >>> Guenter >>> >> >> >> >> -- >> Best regards, >> >> Fu Wei >> Software Engineer >> Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch >> Ph: +86 21 61221326(direct) >> Ph: +86 186 2020 4684 (mobile) >> Room 1512, Regus One Corporate Avenue,Level 15, >> One Corporate Avenue,222 Hubin Road,Huangpu District, >> Shanghai,China 200021 > > > > -- > Best regards, > > Fu Wei > Software Engineer > Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch > Ph: +86 21 61221326(direct) > Ph: +86 186 2020 4684 (mobile) > Room 1512, Regus One Corporate Avenue,Level 15, > One Corporate Avenue,222 Hubin Road,Huangpu District, > Shanghai,China 200021 -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
