Re: [PATCH 09/10] ARM: dts: Add MSHC2 dt node for SD card for exynos3250-artik5-devel board

From: Chanwoo Choi <cw00.choi@samsung.com>
To: Jaehoon Chung <jh80.chung@samsung.com>,
	Krzysztof Kozlowski <k.kozlowski@samsung.com>,
	kgene@kernel.org, s.nawrocki@samsung.com, tomasz.figa@gmail.com
Cc: andi.shyti@samsung.com, inki.dae@samsung.com,
	sw0312.kim@samsung.com, pankaj.dubey@samsung.com,
	linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH 09/10] ARM: dts: Add MSHC2 dt node for SD card for exynos3250-artik5-devel board
Date: Tue, 15 Mar 2016 10:45:14 +0900	[thread overview]
Message-ID: <56E7692A.1020407@samsung.com> (raw)
In-Reply-To: <56E75DC1.7000807@samsung.com>

On 2016년 03월 15일 09:56, Jaehoon Chung wrote:
> On 03/15/2016 09:25 AM, Krzysztof Kozlowski wrote:
>> On 14.03.2016 19:22, Chanwoo Choi wrote:
>>> On 2016년 03월 14일 18:44, Krzysztof Kozlowski wrote:
>>>> On 14.03.2016 17:48, Chanwoo Choi wrote:
>>>>> On 2016년 03월 14일 17:31, Krzysztof Kozlowski wrote:
>>>>>> On 14.03.2016 11:04, Chanwoo Choi wrote:
>>>>>>> From: Jaehoon Chung <jh80.chung@samsung.com>
>>>>>>>
>>>>>>> This patch adds MSHC (Mobile Storage Host Controller) dt node for
>>>>>>> Exynos3250 SoC. MSHC is an interface between the system and the SD card
>>>>>>>
>>>>>>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>>>>>>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>>>> ---
>>>>>>>  arch/arm/boot/dts/exynos3250-artik5-devel.dts | 16 ++++++++++++++++
>>>>>>>  1 file changed, 16 insertions(+)
>>>>>>>
>>>>>>> diff --git a/arch/arm/boot/dts/exynos3250-artik5-devel.dts b/arch/arm/boot/dts/exynos3250-artik5-devel.dts
>>>>>>> index d17c28969118..a371baf8536d 100644
>>>>>>> --- a/arch/arm/boot/dts/exynos3250-artik5-devel.dts
>>>>>>> +++ b/arch/arm/boot/dts/exynos3250-artik5-devel.dts
>>>>>>> @@ -21,6 +21,22 @@
>>>>>>>  			"samsung,exynos3250", "samsung,exynos3";
>>>>>>>  };
>>>>>>>  
>>>>>>> +&mshc_2 {
>>>>>>> +	num-slots = <1>;
>>>>>>> +	cap-sd-highspeed;
>>>>>>> +	disable-wp;
>>>>>>> +	card-detect-delay = <200>;
>>>>>>> +	clock-frequency = <100000000>;
>>>>>>> +	clock-freq-min-max = <400000 100000000>;
>>>>>>> +	samsung,dw-mshc-ciu-div = <1>;
>>>>>>> +	samsung,dw-mshc-sdr-timing = <0 1>;
>>>>>>> +	samsung,dw-mshc-ddr-timing = <1 2>;
>>>>>>> +	pinctrl-names = "default";
>>>>>>> +	pinctrl-0 = <&sd2_cmd &sd2_clk &sd2_cd &sd2_bus1 &sd2_bus4>;
>>>>>>> +	bus-width = <4>;
>>>>>>> +	status = "okay";
>>>>>>
>>>>>> vqmmc-supply = ldo3?
>>>>>
>>>>> ldo3 is always on state because ldo3 is used for various IP in exynos3250.
>>>>> I think that we had better to remain always on state for ldo3.
>>>>
>>>> Yes, I wasn't thinking about toggling ldo3 but about taking the
>>>> regulator here to model the dependencies between components.
>>>
>>> Okay. I'll add it as following:
>>>
>>> 	vmmc-supply = <&ldo18_reg>;
>>> 	vqmmc-supply = <&ldo3>;
>>
>> ldo18 is not used by mshc2. At least my schematics show that LDO3 goes
>> to DVDD_MMC2 (on different board revision that would be ldo18 instead of
>> ldo3, but not both).

ARTIK5 schema document VLDO18 and VLDO3 are connected to DVDD_MMC2_AP.
But, I'm not sure what is meaning. So, I'll drop the 'vmmc-supply'

> 
> It's confusing..but it seems that Krzysztof's opinion is right.
> 
> Best Regards,
> Jaehoon Chung
> 
>>
>> The card itself is powered by VDDFLASH_28/MAIN_BAT.

You're right.

OK, I'll modify it with only vqmmc-supply = <&ldo3>;

Best Regards,
Chanwoo Choi