Messages in this thread | | | Subject | Re: [PATCH v2 02/18] clk: intel: Add clock driver for Intel MIPS SoCs | From | "Zhu, Yi Xin" <> | Date | Mon, 3 Sep 2018 18:47:39 +0800 |
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On 9/1/2018 1:10 AM, Stephen Boyd wrote: > Quoting Zhu, Yi Xin (2018-08-28 23:56:22) >> On 8/28/2018 3:09 AM, Stephen Boyd wrote: >>> Quoting yixin zhu (2018-08-08 01:52:20) >>>> On 8/8/2018 1:50 PM, Stephen Boyd wrote: >>>>>> +/* clock flags definition */ >>>>>> +#define CLOCK_FLAG_VAL_INIT BIT(16) >>>>>> +#define GATE_CLK_HW BIT(17) >>>>>> +#define GATE_CLK_SW BIT(18) >>>>>> +#define GATE_CLK_VT BIT(19) >>>>> What does VT mean? Virtual? >>>> Yes. VT means virtual here. >>>> Will change to GATE_CLK_VIRT. >>>> >>> Is it a hardware concept? Or virtualization with hypervisor? >> Some peripheral drivers want to use same code cross platforms. >> >> But not all platforms provide HW gate clock. So in this case, clock >> driver creates >> >> a virtual gate clock to make it work if no HW gate clock in the SoC. > That's not how things are supposed to work. If a clk isn't there in the > hardware we don't make them up in software so that the consumer software > drivers can keep requesting clks on different platforms. On a different > platform, the driver needs to know that the clks aren't there with a > different compatible string.
OK. Will remove virtual gate clock.
>> >>>>>> +} >>>>>> + >>>>>> +CLK_OF_DECLARE(intel_grx500_cgu, "intel,grx500-cgu", grx500_clk_init); >>>>> Any reason a platform driver can't be used instead of CLK_OF_DECLARE()? >>>> It provides CPU clock which is used in early boot stage. >>>> >>> Ok. What is the CPU clock doing in early boot stage? Some sort of timer >>> frequency? If the driver can be split into two pieces, one to handle the >>> really early stuff that must be in place to get timers up and running >>> and the other to register the rest of the clks that aren't critical from >>> a regular platform driver it would be good. That's preferred model if >>> something is super critical. >> Yes, CPU clock is providing CPU frequency in the early boot stage. >> >> Will put the non-critical clocks in the platform driver. >> >> > Sure the CPU clock is handling frequency, but does that matter for early > boot to get going? If timers aren't involved here then it doesn't sound > like this needs CLK_OF_DECLARE.
Yes, timer is involved here.
CPU frequency get by early stage platform code used in clockevent registration.
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