On 04/11/2016 05:57 AM, Chanwoo Choi wrote: > This patch adds the support of bus frequency feature for sub-blocks which share > the one power line. If each bus depends on the power line, each bus is not able > to change the voltage by oneself. To optimize the power-consumption on runtime, > some buses using the same power line should change the source clock and > regulator at the same time. So, this patch uses the passive governor to support > the bus frequency for all buses which sharing the one power line. > > For example, > > Exynos3250 include the two power line for AXI buses as following: > : VDD_MIF : MIF (Memory Interface) provide the DMC (Dynamic Memory Controller) > with the power (regulator). > : VDD_INT : INT (Internal) provide the various sub-blocks with the power > (regulator). > > Each bus is included in as follwoing block. In the case of VDD_MIF, only DMC bus > use the power line. So, there is no any depencency between buese. But, in the > case of VDD_INT, various buses share the one power line of VDD_INT. We need to > make the depenency between buses. When using passive governor, there is no > problem to support the bus frequency as DVFS for all buses. One bus should be > operated as the parent bus device which gathering the current load of INT block > and then decides the new frequency with some governors except of passive > governor. After deciding the new frequency by the parent bus device, the rest > bus devices will change the each source clock according to new frequency of the > parent bus device. > > - MIF (Memory Interface) block > : VDD_MIF |--- DMC > > - INT (Internal) block > : VDD_INT |--- LEFTBUS (parent) > |--- PERIL > |--- MFC > |--- G3D > |--- RIGHTBUS > |--- FSYS > |--- LCD0 > |--- PERIR > |--- ISP > |--- CAM > > Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> > [tjakobi: Reported debugfs error during booting and cw00.choi fix it.] > Reported-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx> > Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> > --- > drivers/devfreq/Kconfig | 1 + > drivers/devfreq/exynos-bus.c | 219 ++++++++++++++++++++++++++++++++++--------- > 2 files changed, 174 insertions(+), 46 deletions(-) Acked-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
