On 06/17/2014 06:15 PM, Stephen Warren wrote: > On 06/17/2014 06:16 AM, Tomeu Vizoso wrote: >> On 06/16/2014 10:02 PM, Stephen Warren wrote: >>> On 06/16/2014 07:35 AM, Tomeu Vizoso wrote: >>>> +#ifdef CONFIG_TEGRA124_EMC >>>> +int tegra124_emc_reserve_bandwidth(unsigned int consumer, unsigned >>>> long rate); >>>> +void tegra124_emc_set_floor(unsigned long freq); >>>> +void tegra124_emc_set_ceiling(unsigned long freq); >>>> +#else >>>> +int tegra124_emc_reserve_bandwidth(unsigned int consumer, unsigned >>>> long rate) >>>> +{ return -ENODEV; } >>>> +void tegra124_emc_set_floor(unsigned long freq) >>>> +{ return; } >>>> +void tegra124_emc_set_ceiling(unsigned long freq) >>>> +{ return; } >>>> +#endif >>> >>> I'll repeat what I said off-list so that we can have the whole >>> conversation on the list: >>> >>> That looks like a custom Tegra-specific API. I think it'd be much better >>> to integrate this into the common clock framework as a standard clock >>> constraints API. There are other use-cases for clock constraints besides >>> EMC scaling (e.g. some in audio on Tegra, and I'm sure many on other >>> SoCs too). >> >> Yes, I wrote a bit in the cover letter about our requirements and how >> they map to the CCF. Could you please comment on that? > > My comments remain the same. I believe this is something that belongs in > the clock driver, or at the least, some API that takes a struct clock as > its parameter, so that drivers can use the existing DT clock lookup > mechanism.
Ok, let me put this strawman here to see if I have gotten close to what you have in mind: * add per-client accounting (Rabin's patches referenced before) * add clk_set_floor, to be used by cpufreq, load stats, etc. * add clk_set_ceiling, to be used by battery drivers, thermal, etc. * an EMC driver would collect bandwidth and latency requests from consumers and call clk_set_floor on the EMC clock. * the EMC driver would also register for rate change notifications in the EMC clock and would update the latency allowance registers at that point. How does it sound? Regards, Tomeu