Re: [PATCH v2 01/10] clk: sunxi-ng: Add interface to query or configure MMC timing modes.

Chen-Yu Tsai
2017-07-21T07:23:15Z

On Fri, Jul 21, 2017 at 3:18 PM, Maxime Ripard
<maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote:
> Hi,
>
> On Thu, Jul 20, 2017 at 11:44:43AM +0800, Chen-Yu Tsai wrote:
>> Starting with the A83T SoC, Allwinner introduced a new timing mode for
>> its MMC clocks. The new mode changes how the MMC controller sample and
>> output clocks are delayed to match chip and board specifics. There are
>> two controls for this, one on the CCU side controlling how the clocks
>> behave, and one in the MMC controller controlling what inputs to take
>> and how to route them.
>>
>> In the old mode, the MMC clock had 2 child clocks providing the output
>> and sample clocks, which could be delayed by a number of clock cycles
>> measured from the MMC clock's parent.
>>
>> With the new mode, the 2 delay clocks are no longer active. Instead,
>> the delays and associated controls are moved into the MMC controller.
>> The output of the MMC clock is also halved.
>>
>> The difference in how things are wired between the modes means that the
>> clock controls and the MMC controls must match. To achieve this in a
>> clear, explicit way, we introduce two functions for the MMC driver to
>> use: one queries the hardware for the current mode set, and the other
>> allows the MMC driver to request a mode.
>>
>> Signed-off-by: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
>> ---
>> drivers/clk/sunxi-ng/Makefile | 1 +
>> drivers/clk/sunxi-ng/ccu_common.h | 5 +++
>> drivers/clk/sunxi-ng/ccu_mmc_timing.c | 73 +++++++++++++++++++++++++++++++++++
>> include/linux/clk/sunxi-ng.h | 35 +++++++++++++++++
>> 4 files changed, 114 insertions(+)
>> create mode 100644 drivers/clk/sunxi-ng/ccu_mmc_timing.c
>> create mode 100644 include/linux/clk/sunxi-ng.h
>>
>> diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile
>> index 0c45fa50283d..45a5910379a5 100644
>> --- a/drivers/clk/sunxi-ng/Makefile
>> +++ b/drivers/clk/sunxi-ng/Makefile
>> @@ -1,5 +1,6 @@
>> # Common objects
>> lib-$(CONFIG_SUNXI_CCU) += ccu_common.o
>> +lib-$(CONFIG_SUNXI_CCU) += ccu_mmc_timing.o
>> lib-$(CONFIG_SUNXI_CCU) += ccu_reset.o
>>
>> # Base clock types
>> diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h
>> index d6fdd7a789aa..1e2761c53f06 100644
>> --- a/drivers/clk/sunxi-ng/ccu_common.h
>> +++ b/drivers/clk/sunxi-ng/ccu_common.h
>> @@ -23,6 +23,11 @@
>> #define CCU_FEATURE_FIXED_POSTDIV BIT(3)
>> #define CCU_FEATURE_ALL_PREDIV BIT(4)
>> #define CCU_FEATURE_LOCK_REG BIT(5)
>> +#define CCU_FEATURE_MMC_TIMING_SWITCH BIT(6)
>> +#define CCU_FEATURE_MMC_ALWAYS_NEW BIT(7)
>
> Didn't we agree on removing that flag?

Indeed. I thought I had finished the cleanup. But apparently I didn't.
Sorry about that.

ChenYu

>
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com
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