Hi Guenter, On 2021/5/11 11:52, Guenter Roeck wrote: > On 5/10/21 7:49 PM, Shaokun Zhang wrote: >> Hi Guenter, >> >> On 2021/5/10 21:16, Guenter Roeck wrote: >>> On 5/10/21 1:25 AM, Shaokun Zhang wrote: >>>> Hi Guenter, >>>> >>>> On 2021/5/10 12:25, Guenter Roeck wrote: >>>>> On 5/9/21 8:41 PM, Shaokun Zhang wrote: >>>>>> Arm Base System Architecture 1.0[1] has introduced watchdog >>>>>> revision 1 that increases the length the watchdog offset >>>>> >>>>> Is that how they call the watchdog count register ? >>>>> >>>> >>>> I think yes. >>>> >>>>> Also, doesn't that mean that the maximum timeout supported >>>>> by the hardware is now larger ? >>>> >>>> No, maximum timeout is the same. But the clock can be higher than >>>> before. For Armv8.6, The frequency of CNTFRQ_EL0 is standardized to >>>> a frequency of 1GHz which will set gwdt->clk. If the timeout is >>>> greater than 4(second), the 32-bit counter(WOR) is not enough. >>>> >>> >>> The maximuma timeout is limited with >>> >>> wdd->max_hw_heartbeat_ms = U32_MAX / gwdt->clk * 1000; >>>> You did not update that calculation. That means that the maximuma >>> timeout is still U32_MAX / gwdt->clk * 1000, which still fits >>> into 32 bit. >> >> Correct, I will fix this in next version. >> >>> >>> Please correct me if I am missing something. >>> >> >> My bad, you are right. The maximum timeout shall be >> 0xFFFF.FFFF.FFFF / 1000.000.000(1GHz) which is larger than before >> 0xFFFF.FFFF / 100.000.000(100MHz) by the hardware. >> >> Can I do like this, after the version is got and check the version? >> sbsa_gwdt_set_timeout(wdd, wdd->timeout); >> + sbsa_gwdt_get_version(wdd); >> + if (wdd->version > 0) >> + wdd->max_hw_heartbeat_ms = GENMASK_ULL(47, 0) / gwdt->clk * 1000; >> > > I would suggest to set max_hw_heartbeat_ms in one place > to avoid confusion. Either check the version earlier, > or move setting both max_hw_heartbeat_ms values > after the call to sbsa_gwdt_get_version(). > Got it, I will follow the former that many members in @wdd are initialized closely. Thanks again, Shaokun > Thanks, > Guenter > > .
