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SubjectRe: [PATCH v9 06/20] PM / devfreq: exynos: Add support of bus frequency of sub-blocks using passive governor
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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@samsung.com>
> [tjakobi: Reported debugfs error during booting and cw00.choi fix it.]
> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
> ---
> drivers/devfreq/Kconfig | 1 +
> drivers/devfreq/exynos-bus.c | 219 ++++++++++++++++++++++++++++++++++---------
> 2 files changed, 174 insertions(+), 46 deletions(-)


Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Best regards,
Krzysztof

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