On Thu, 2013-10-17 at 00:51 -0500, Wang Dongsheng-B40534 wrote: > > > -----Original Message----- > > From: Bhushan Bharat-R65777 > > Sent: Thursday, October 17, 2013 11:20 AM > > To: Wang Dongsheng-B40534; Wood Scott-B07421 > > Cc: linuxppc-dev@lists.ozlabs.org > > Subject: RE: [PATCH v5 4/4] powerpc/85xx: add sysfs for pw20 state and > > altivec idle > > > > > > > > > -----Original Message----- > > > From: Wang Dongsheng-B40534 > > > Sent: Thursday, October 17, 2013 8:16 AM > > > To: Bhushan Bharat-R65777; Wood Scott-B07421 > > > Cc: linuxppc-dev@lists.ozlabs.org > > > Subject: RE: [PATCH v5 4/4] powerpc/85xx: add sysfs for pw20 state and > > > altivec idle > > > > > > > > > > > > > -----Original Message----- > > > > From: Bhushan Bharat-R65777 > > > > Sent: Thursday, October 17, 2013 1:01 AM > > > > To: Wang Dongsheng-B40534; Wood Scott-B07421 > > > > Cc: linuxppc-dev@lists.ozlabs.org > > > > Subject: RE: [PATCH v5 4/4] powerpc/85xx: add sysfs for pw20 state > > > > and altivec idle > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > From: Wang Dongsheng-B40534 > > > > > Sent: Tuesday, October 15, 2013 2:51 PM > > > > > To: Wood Scott-B07421 > > > > > Cc: Bhushan Bharat-R65777; linuxppc-dev@lists.ozlabs.org; Wang > > > > Dongsheng-B40534 > > > > > Subject: [PATCH v5 4/4] powerpc/85xx: add sysfs for pw20 state and > > > > altivec idle > > > > > > > > > > +static ssize_t show_pw20_wait_time(struct device *dev, > > > > > + struct device_attribute *attr, char > > > > > *buf) { > > > > > + u32 value; > > > > > + u64 tb_cycle; > > > > > + s64 time; > > > > > + > > > > > + unsigned int cpu = dev->id; > > > > > + > > > > > + if (!pw20_wt) { > > > > > + smp_call_function_single(cpu, do_show_pwrmgtcr0, &value, > > 1); > > > > > + value = (value & PWRMGTCR0_PW20_ENT) >> > > > > > + PWRMGTCR0_PW20_ENT_SHIFT; > > > > > + > > > > > + tb_cycle = (1 << (MAX_BIT - value)) * 2; > > > > > > > > Is value = 0 and value = 1 legal? These will make tb_cycle = 0, > > > > > > > > > + time = div_u64(tb_cycle * 1000, tb_ticks_per_usec) - 1; > > > > > > > > And time = -1; > > > > > > > Please look at the end of the function, :) > > > > > > "return sprintf(buf, "%llu\n", time > 0 ? time : 0);" > > > > I know you return 0 if value = 0/1, my question was that, is this correct > > as per specification? > > > > Ahh, also for "value" upto 7 you will return 0, no? > > > If value = 0, MAX_BIT - value = 63 > tb_cycle = 0xffffffff_ffffffff,
Actually, tb_cycle will be undefined because you shifted a 32-bit value (1) by more than 31 bits. s/1/1ULL/ > tb_cycle * 1000 will overflow, but this situation is not possible. > Because if the "value = 0" means this feature will be "disable". > Now The default wait bit is 50(MAX_BIT - value, value = 13), the > PW20/Altivec Idle wait entry time is about 1ms, this time is very long > for wait idle time, and it's cannot be increased(means (MAX_BIT - > value) cannot greater than 50). Why can it not be increased? -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev