[PATCH v2 0/3] clk: sunxi: Add muxable AHB clock to fix hstimer issues

Chen-Yu Tsai wens at csie.org
Wed Mar 25 13:13:46 PDT 2015

On Wed, Mar 25, 2015 at 11:51 AM, Maxime Ripard
<maxime.ripard at free-electrons.com> wrote:
> On Wed, Mar 25, 2015 at 01:22:06AM +0800, Chen-Yu Tsai wrote:
>> Hi everyone,
>> This is v2 of the sun5i muxable AHB clock series.
>> Changes since v1:
>>   - Dropped patches 1~3 that are merged
>>   - Extend comments to clarify what the "base factor clock" refers to,
>>     and what the divs clocks outputs should be.
>> This series adds support for the muxable ahb clock on sun5/7i. The mux
>> has inputs such as the axi clock, the cpu clock on sun5i, and pll6 with
>> various dividers. The goal is to have ahb muxed to pll6, which should
>> be a fixed rate albeit configurable clock. This fixes issues with
>> cpufreq changing the cpu frequency, which would affect the hstimer
>> clocked from ahb.
>> Patch 1 makes divs clocks explicitly specify in the driver which output
>> is the base factor clock, instead of always putting it in last. This is
>> done to ensure DT bindings compatibility when we add outputs.
>> Patch 2 adds the new pll6/4 output, which is used on sun7i as an input
>> to ahb mux.
>> Patch 3 updates the dtsi files with the new drivers.
>> The series is also available at
>>     https://github.com/wens/linux/commits/sun5i-ahb-v2
> Applied all three. I think it would be great to convert the later SoCs
> to that too, just to make sure we have the same policy on all SoCs.

For sun6i this is already doable. We just move the assignment from the
dmaengine node to the clock node.

For sun8i the default divider results in 300 MHz for AHB, which might
be too fast. And we can't do clock rate assignment yet. The clock
drivers need to be split out.

For sun9i it is already the default.


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