Re: [PATCH 3/3] ARM: dts: exynos5422-odroidxu3: Added UHS-I bus speed support

[Alim Akhtar]

On Wed, Oct 14, 2015 at 7:22 AM, Krzysztof Kozlowski
<k.kozlowski@xxxxxxxxxxx> wrote:
> On 14.10.2015 10:40, Jaehoon Chung wrote:
>> On 10/14/2015 10:15 AM, Krzysztof Kozlowski wrote:
>>> On 14.10.2015 10:06, Alim Akhtar wrote:
>>>> +Doug
>>>> Hello,
>>>> AFAIR, dw_mmc host controller does support UHS-I [1], specially SDR50
>>>> and SDR104 modes.
>>>>
>>>> [1]: http://www.spinics.net/lists/linux-mmc/msg28186.html
>>>>
>>>> What I remember is, one need to set "broken-cd" property also in order
>>>> to make it work because of the vqmmc and vmmc connection on board. I
>>>> didn't find the link right now, but you can search on the web, there
>>>> was a long discussion about handling this.
>>>> Have not checked it recently, so not sure if this got broken somehow.
>>>>
>>>
>>> Please, don't top post.
>>>
>>> I am not a SD/MMC specialist (I do not feel enough confident in its
>>> internals) but the datasheet for 5422 does not mention UHS. However it
>>> mentions "High Speed DDR Mode with 200 MHz clock rate (HS400)". This
>>> does not look like UHS...
>>
>> You're right. It's not UHS mode. it mentions eMMC's HS400 mode.
>> UHS and HS400 are difference mode.
>>
>> eMMC mode are supported
>>
>>> https://www.sdcard.org/developers/overview/bus_speed/
>>> This of course is not a definite proof that 5422 does not support UHS. I
>>> am just saying that I couldn't find any information that *it does*.
>>
>> Well, I think you want to know whether it supported or not.
>> Then you can find the information at User manual.
>> In mobile storage part of User manual, it described the overview.
>> Mobile storage host supports these specification:
>> - Secure Digital memory (SD memory version 3.0)
>> - Secure Digital I/O SDIO (SDIO version 3.0)
>> - etc...
>>
>> SD3.0 is supported UHS-I mode.
>> If user manual of exynos5422 is mentioned this specification, it should be supported UHS-I mode.
>
> Thanks! Indeed datasheet mentions that supported SD and SDIO is version
> 3.0 (not 3.01... which seems irrelevant because 3.0 introduced UHS-I,
> right?).
>
Yes, your understanding is right. SD3.0 does includes UHS-I.

> Best regards,
> Krzysztof



-- 
Regards,
Alim
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