[PATCH 3/3] ARM: dts: exynos5422-odroidxu3: Added UHS-I bus speed support
linux.amoon at gmail.com
Mon Oct 19 03:11:44 PDT 2015
Hi Doug/ Krzysztof ,
On 15 October 2015 at 04:10, Doug Anderson <dianders at chromium.org> wrote:
> On Tue, Oct 13, 2015 at 6:06 PM, Alim Akhtar <alim.akhtar at gmail.com> wrote:
>> AFAIR, dw_mmc host controller does support UHS-I , specially SDR50
>> and SDR104 modes.
>> : 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.
> Right. It _shouldn't_ be possible to add "vmmc/vqmmc" supplies to
> your DTS (which you do in patch 2/3) and also to use the "gpc2-2" pin
> for card detect (even if you configure it as a GPIO). Once you add
> "vmmc/vqmmc" then Linux ought to be turning these regulators off when
> no card is plugged in. Presumably the "vqmmc" regulator is hooked up
> to the "VDDQ_MMC2". If you look in the user manual for 5422 you can
> see that "GPC2/SD_2_CDn" has power domain "VDDQ_MMC2". Thus you
> really shouldn't be using that pin when vqmmc is off. I think at some
> point someone claimed that it still worked for them, but nobody could
> ever explain why. Full discussion at
> In case it matters, comments on stuff from earlier in the thread:
> * As people pointed out, exynos5422 certainly supports all these modes
> (including DDR50) in the SoC.
> * Just because the SoC supports these modes doesn't mean that the
> boards do, which is why the SoC .dtsi doesn't include them. Thus,
> this patch is "right" in that it changes a board-specific file.
> * As Krzysztof points out this board doesn't "add" support but rather
> "enables" support. The distinction is subtle.
> * You might be able to get DDR50 working, but probably better to just
> start with SDR modes. Previously I never attempted to get DDR50 cards
> working, so possibly the software needs extra work?
Thanks for clarifying all the background details on the mmc changes.
Here is what I would conclude from the previous mail chain's.
1 Drop the cd-gpios changes. pinctrl-0 changes.
2 Fix the regulator changes for vmmc/vqmmc with disable of regulator-always-on;
3 Drop this UHS-I changes as if now.
Is this ok with you.
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