linux-kernel - Re: [PATCH v6 06/10] dt-bindings: memory-controllers: add Exynos5422 DMC device description

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Date:   Thu, 2 May 2019 10:35:22 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Lukasz Luba <l.luba@...tner.samsung.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Cc:     b.zolnierkie@...sung.com, krzk@...nel.org, kgene@...nel.org,
        kyungmin.park@...sung.com, m.szyprowski@...sung.com,
        s.nawrocki@...sung.com, myungjoo.ham@...sung.com,
        keescook@...omium.org, tony@...mide.com, jroedel@...e.de,
        treding@...dia.com, digetx@...il.com, willy.mh.wolff.ml@...il.com
Subject: Re: [PATCH v6 06/10] dt-bindings: memory-controllers: add
 Exynos5422 DMC device description

Hi Lukasz,

On 19. 5. 1. 오전 5:30, Lukasz Luba wrote:
> Hi Chanwoo,
> 
> On 4/30/19 6:46 AM, Chanwoo Choi wrote:
>> On 19. 4. 19. 오후 11:19, Lukasz Luba wrote:
>>> The patch adds description for DT binding for a new Exynos5422 Dynamic
>>> Memory Controller device.
>>>
>>> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
>>> ---
>>>   .../bindings/memory-controllers/exynos5422-dmc.txt | 73 ++++++++++++++++++++++
>>>   1 file changed, 73 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt b/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
>>> new file mode 100644
>>> index 0000000..133b3cc
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/memory-controllers/exynos5422-dmc.txt
>>> @@ -0,0 +1,73 @@
>>> +* Exynos5422 frequency and voltage scaling for Dynamic Memory Controller device
>>> +
>>> +The Samsung Exynos5422 SoC has DMC (Dynamic Memory Controller) to which the DRAM
>>> +memory chips are connected. The driver is to monitor the controller in runtime
>>> +and switch frequency and voltage. To monitor the usage of the controller in
>>> +runtime, the driver uses the PPMU (Platform Performance Monitoring Unit), which
>>> +is able to measure the current load of the memory.
>>> +When 'userspace' governor is used for the driver, an application is able to
>>> +switch the DMC and memory frequency.
>>> +
>>> +Required properties for DMC device for Exynos5422:
>>> +- compatible: Should be "samsung,exynos5422-bus".
>>
>> As I already mentioned on many times, it is not fixed.
>> You have to fix it as following:
>> - exynos5422-bus -> exynos5422-dmc
> I don't know how I missed it on my list. My apologies.
>>
>>> +- clock-names : the name of clock used by the bus, "bus".
>>
>> The below examples doesn't contain the 'bus' clock name.
> True. Thank you for pointing this out. I will it.
> 
> Regards,
> Lukasz
>>
>>> +- clocks : phandles for clock specified in "clock-names" property.
>>> +- devfreq-events : phandles for PPMU devices connected to this DMC.
>>> +- vdd-supply : phandle for voltage regulator which is connected.
>>> +- reg : registers of two CDREX controllers, chip information, clocks subsystem.
>>> +- operating-points-v2 : phandle for OPPs described in v2 definition.
>>> +- device-handle : phandle of the connected DRAM memory device. For more
>>> +	information please refer to Documentation
>>> +- devfreq-events : phandles of the PPMU events used by the controller.
>>> +
>>> +Example:
>>> +
>>> +	ppmu_dmc0_0: ppmu@...00000 {
>>> +		compatible = "samsung,exynos-ppmu";
>>> +		reg = <0x10d00000 0x2000>;
>>> +		clocks = <&clock CLK_PCLK_PPMU_DREX0_0>;
>>> +		clock-names = "ppmu";
>>> +		status = "okay";
>>> +		events {
>>> +			ppmu_event_dmc0_0: ppmu-event3-dmc0_0 {
>>> +				event-name = "ppmu-event3-dmc0_0";
>>> +			};
>>> +		};
>>> +	};
>>> +
>>> +	dmc: memory-controller@...20000 {
>>> +		compatible = "samsung,exynos5422-dmc";
>>> +		reg = <0x10c20000 0x10000>, <0x10c30000 0x10000>,
>>> +			<0x10000000 0x1000>, <0x10030000 0x1000>;

As I discussed about the register region of clock subsystem
with Sylwester on patch[1], I expected that you used the regmap
interface to control the register region of clock subsystem.

But, this dt-binding documents doesn't include any information
about regmap interface.

[1] https://lkml.org/lkml/2019/3/6/878

>>> +		clocks = 	<&clock CLK_FOUT_SPLL>,
>>> +				<&clock CLK_MOUT_SCLK_SPLL>,
>>> +				<&clock CLK_FF_DOUT_SPLL2>,
>>> +				<&clock CLK_FOUT_BPLL>,
>>> +				<&clock CLK_MOUT_BPLL>,
>>> +				<&clock CLK_SCLK_BPLL>,
>>> +				<&clock CLK_MOUT_MX_MSPLL_CCORE>,
>>> +				<&clock CLK_MOUT_MX_MSPLL_CCORE_PHY>,
>>> +				<&clock CLK_MOUT_MCLK_CDREX>,
>>> +				<&clock CLK_DOUT_CLK2X_PHY0>,
>>> +				<&clock CLK_CLKM_PHY0>,
>>> +				<&clock CLK_CLKM_PHY1>;
>>> +		clock-names =	"fout_spll",
>>> +				"mout_sclk_spll",
>>> +				"ff_dout_spll2",
>>> +				"fout_bpll",
>>> +				"mout_bpll",
>>> +				"sclk_bpll",
>>> +				"mout_mx_mspll_ccore",
>>> +				"mout_mx_mspll_ccore_phy",
>>> +				"mout_mclk_cdrex",
>>> +				"dout_clk2x_phy0",
>>> +				"clkm_phy0",
>>> +			        "clkm_phy1";
>>> +		status = "okay";
>>> +		operating-points-v2 = <&dmc_opp_table>;
>>> +		devfreq-events = <&ppmu_event3_dmc0_0>,	<&ppmu_event3_dmc0_1>,
>>> +				<&ppmu_event3_dmc1_0>, <&ppmu_event3_dmc1_1>;
>>> +		operating-points-v2 = <&dmc_opp_table>;
>>> +		device-handle = <&samsung_K3QF2F20DB>;
>>> +		vdd-supply = <&buck1_reg>;
>>> +	};
>>>
>>
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics