Messages in this thread | | | Subject | Re: [PATCH] firmware: arm_scmi: fix divide by zero when sustained_perf_level is zero | From | Sudeep Holla <> | Date | Thu, 6 Sep 2018 15:38:13 +0100 |
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On 06/09/18 14:17, Quentin Perret wrote: > Hi Sudeep, > > On Wednesday 05 Sep 2018 at 17:38:11 (+0100), Sudeep Holla wrote: >> @@ -166,7 +166,12 @@ scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain, >> le32_to_cpu(attr->sustained_freq_khz); >> dom_info->sustained_perf_level = >> le32_to_cpu(attr->sustained_perf_level); >> - dom_info->mult_factor = (dom_info->sustained_freq_khz * 1000) / >> + if (!dom_info->sustained_freq_khz || >> + !dom_info->sustained_perf_level) >> + dom_info->mult_factor = 1; > > I'm sorry I missed that the first time I reviewed this patch, but after > discussing with Ionela, we found out that there is actually a case where > this could be a problem. If you have perf levels that are 1,2,3,4 (for > example), then with mult_factor=1 you'll register OPPs at 1Hz, 2Hz, 3Hz, > 4Hz into PM_OPP. And that will be turned into 0 KHz for all of them at > the CPUFreq level when divided by 1000 in dev_pm_opp_init_cpufreq_table(). >
Good find.
> I guess a quick fix would be to have a default mult_factor of 1000 ... >
I agree.
> What do you think ?
I will respin and send.
-- Regards, Sudeep
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