Re: [PATCHv2] ARM: dts: use vmmc-supply of emmc/sd for exynos5422-odroidxu3

[Anand Moon]

Hi Krzysztof,

On 30 November 2015 at 11:12, Krzysztof Kozlowski
<k.kozlowski@xxxxxxxxxxx> wrote:
> On 27.11.2015 15:42, Anand Moon wrote:
>> hi Krzysztof,
>>
>> On 22 October 2015 at 18:34, Anand Moon <linux.amoon@xxxxxxxxx> wrote:
>>> hi Krzysztof,
>>>
>>> On 22 October 2015 at 06:31, Krzysztof Kozlowski
>>> <k.kozlowski@xxxxxxxxxxx> wrote:
>>>> On 20.10.2015 21:56, Anand Moon wrote:
>>>>> Changes need for host controller to detect UHS-I highspeed cards.
>>>>> Changes in VDDQ_MMC2 voltage range help scale
>>>>> the required voltage to detect and load the microSD cards.
>>>>
>>>> Thanks for updating description of commit.
>>>>
>>>>>
>>>>> Signed-off-by: Anand Moon <linux.amoon@xxxxxxxxx>
>>>>> ---
>>>>> Changes based on git://git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung.git v4.4-next/dt-samsung branch
>>>>>
>>>>> Changes:
>>>>> Drop the ranp_delay for LDO9.
>>>>>
>>>>> Thanks to : Krzysztof, Doug Anderson, Jaehoon Chung for helping
>>>>> me out figure out the mmc core requirement.
>>>>>
>>>>> Also drop the previous changes:
>>>>> use cd-gpio method to detect sd-card.
>>>>> Added UHS-I bus speed support.
>>>>>
>>>>> [    4.713553] random: nonblocking pool is initialized
>>>>> [    4.718423] 14530000.hdmi supply hdmi-en not found, using dummy regulator
>>>>> [    4.726206] exynos-drm exynos-drm: bound 14400000.fimd (ops fimd_component_ops)
>>>>> [    4.732555] exynos-drm exynos-drm: bound 14450000.mixer (ops mixer_component_ops)
>>>>> [    4.740180] exynos-drm exynos-drm: bound 14530000.hdmi (ops hdmi_component_ops)
>>>>> [    4.746936] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>>>>> [    4.753428] [drm] No driver support for vblank timestamp query.
>>>>> [    4.940794] Console: switching to colour frame buffer device 274x77
>>>>> [    4.995344] exynos-drm exynos-drm: fb0:  frame buffer device
>>>>> [    5.024573] [drm] Initialized exynos 1.0.0 20110530 on minor 0
>>>>> [    5.031164] exynos-dwc3 usb@12000000: no suspend clk specified
>>>>> [    5.054571] usb 2-1: new full-speed USB device number 2 using exynos-ohci
>>>>> [    5.159527] dwmmc_exynos 12220000.mmc: Busy; trying anyway
>>>>> [    5.163705] mmc_host mmc1: Timeout sending command (cmd 0x202000 arg 0x0 status 0x0)
>>>>> ---
>>>>>  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi | 7 ++++++-
>>>>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
>>>>> index 1af5bdc..a4be3e0 100644
>>>>> --- a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
>>>>> +++ b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
>>>>> @@ -182,9 +182,10 @@
>>>>>
>>>>>                       ldo13_reg: LDO13 {
>>>>>                               regulator-name = "vdd_ldo13";
>>>>> -                             regulator-min-microvolt = <2800000>;
>>>>> +                             regulator-min-microvolt = <1800000>;
>>>>
>>>> You did not convinced me in previous discussion about the change to
>>>> 1.8V. I said that:
>>>>> On the same diagram few lines below:
>>>>> VDDQ_MMC2: 2.8V 250mA
>>>>
>>>> You responded:
>>>>> You are correct.
>>>>
>>>> So I am confused. Are you sure that this SD card block can/should
>>>> operate on 1.8V? Have you actually tried this?
>>>>
>>>
>>> Look like I missed this point. Here is the link I would like to share.
>>>
>>> http://www.hjreggel.net/cardspeed/cs_sdxc.html
>>> Section: Summary of SD modes
>>>
>>> https://en.wikipedia.org/wiki/Secure_Digital
>>> Section: Power consumption
>>>
>>> Their different requirement for voltage requirement for UHS-I, the max
>>> value is around 3.3V
>>
>> Do you have any comment on this voltage selection for UHS-I card (1.8V).
>
> I asked whether you tried this, whether setting real 1.8V works fine.
> You did not respond. As you can see on Odroid schematics, the VDDQ for
> MMC[01] operates under 1.8V.
>
> The VDDQ for MMC2 - under 2.8V.
>
> In commit description you mentioned that this voltage "helps scale the
> required voltage to detect and load the microSD cards". What does it
> mean "help"? I would expect that detecting and loading of microSD cards
> either works or does not work. I am not sure how does it help.
>
> Best regards,
> Krzysztof

I will fix the commit message.

Earlier around v4.2 detection of UHS-I card was not working,but now it
seen to work in v4.4 kernel.
May be some driver issue which might have been fixed.

I am just trying to set the voltage range for LDO13 from 1.8V (min) to
2.8V (max).
If setting this is wrong according to datasheet then I will drop this setting.

-Anand Moon
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