Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[Siarhei Siamashka]

On Mon, 19 Sep 2016 09:07:39 -0700 (PDT)
TsvetanUsunov  wrote:

> Hi,
> 
> We make our final touch of A64-OLinuXino PCB and there we add option eMMC 
> Flash to work on dual voltages 1.8V and 3.3V.
> The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that when 
> A64 boots and AXP803 is not initialized it outputs default 0.8V then after 
> initialization driver takes care to drive it  1.8V or 3.3V.
> This makes impossible to boot from eMMC which is not good. We now think for 
> solution which to drive eMMC at 3.3V initially when AXP803 output is below 
> 1.8V but this adds unnecessary hardware complexity.
> For hardware point of view it will be much more simplier if dedigated A64 
> GPIO is used and initially is pulled down and after AXP803 is initialized 
> is pulled up.
> How would you suggest us to implement it? Will this additional GPIO create 
> troubles in eMMC driver philosophy?
> For the SDMMC we are still hesitating what to do as we don't know if the 
> card which will be inserted will support low voltage and higher speeds at 
> all. Also eMMC Flash and SDMMC card should be driven by separate voltages, 
> as they may work in any combinations.
> This means we need another AXP803 LDO and another GPIO for the SDMMC card.
> 
> By the way the current eMMC from Micron we use has 11MB Write speed no 
> matter what is the voltage and this is written in the datasheet, so maybe 
> we should switch and add this dual voltage to the SD MMC where someone 
> could use SD MMC card supporting higher clocks?
> 
> I would love to hear your opinion.

Hi,

I have only skimmed through the JEDEC MMC standard, but got an
impression that it is perfectly safe to run dual voltage cards at
1.8V voltage all the time. At least that's how I'm interpreting
the first and the last paragraphs of the "7.4.2 Operating voltage
range validation" section of the JESD84-A44 MMC Version 4.4 standard.

Basically, it looks like when you are running with the 1.8V
voltage, you can do everything that is possible with 3.3V and
it just additionally allows higher speed modes (HS200).
Presumably also consuming less power.

The init sequence also involves starting the card with 3.3V. Then doing
the voltage negotiation. Then powering the card off, switching to 1.8V
and basically repeating the same steps. But if the card is 1.8V
capable, then the initial negotiation step looks redundant. It can
also run at 1.8V instead of 3.3V without affecting anything.

Thus it seems to be a ridiculous idea to implement the runtime
1.8V/3.3V voltage switching for a dual voltage capable eMMC chip
that is soldered to the PCB. You can probably just connect it to
a fixed 1.8V voltage regulator and be done with that.

The voltage switching and negotiation seems to be only useful
for removable SD cards, where you don't have any idea if the
connected SD card actually supports 1.8V or not.

But I'm not an eMMC expert, so please correct me if I got
everything wrong.

-- 
Best regards,
Siarhei Siamashka

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Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[jonsm...@gmail.com]

On Tue, Sep 20, 2016 at 11:50 AM, Andre Przywara  wrote:
> Hi,
>
> On 20/09/16 15:49, jonsm...@gmail.com wrote:
>> On Tue, Sep 20, 2016 at 10:45 AM, jonsm...@gmail.com  
>> wrote:
>>> On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov  
>>> wrote:


 понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа:
>
> Hi,
>
> On 19-09-16 18:07, TsvetanUsunov wrote:
>> Hi,
>>
>> We make our final touch of A64-OLinuXino PCB and there we add option
>> eMMC Flash to work on dual voltages 1.8V and 3.3V.
>> The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that
>> when A64 boots and AXP803 is not initialized it outputs default 0.8V then
>> after initialization driver takes care to drive it  1.8V or 3.3V.
>> This makes impossible to boot from eMMC which is not good. We now think
>> for solution which to drive eMMC at 3.3V initially when AXP803 output is
>> below 1.8V but this adds unnecessary hardware complexity.
>> For hardware point of view it will be much more simplier if dedigated
>> A64 GPIO is used and initially is pulled down and after AXP803 is
>> initialized is pulled up.
>
> Ok, so what your suggesting is:
>
> axp803-ldo-io1  -\
>[mux]---> mmc-supply
> Fixed-3.3v --/  |
>  |
>  |mux-control
> A64 gpio out/
>
> Note the above ascii-art requires a fixed-width font.
>
> With a pull-down (or pull-up) to fix the mux in a certain position when
> the gpio is in tri-state ?
>
> As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator
> framework should be able to deal with, and in u-boot we can just
> keep things at 3.3v.
>
>> How would you suggest us to implement it? Will this additional GPIO
>> create troubles in eMMC driver philosophy?
>
> For the Linux mmc driver the mmc-supply is abstracted as a regulator,
> and the regulator framework should be able to deal with any setup
> you can come up with.
>
>> For the SDMMC we are still hesitating what to do as we don't know if the
>> card which will be inserted will support low voltage and higher speeds at
>> all.
>
> As long as you default to 3.3v then the kernel's sd subsystem can
> dynamically switch voltage (through e.g. the gpio) if the card
> advertises it supports low voltage. Note that you're planning
> the first board to implement this that I know off, so the sunxi-mmc
> kernel driver will need some work to support voltage switching,
> but in the mean time things should work fine at 3.3v.
>
>> Also eMMC Flash and SDMMC card should be driven by separate voltages, as
>> they may work in any combinations.
>
> Ack, right, as said both cards should come up with 3.3v and then
> a new voltage will be negotiated before switching, so this definitely
> needs to be per card.
>
>> This means we need another AXP803 LDO and another GPIO for the SDMMC
>> card.
>
> Right


 Micron eMMC chips we use do not support higher clock at lower voltage, so
 the way we wired the schematic right now makes no much sense.
 I check for other vendors but also can't find such eMMC chip, if someone
 knows please let us know to investigate more?

 So in this case makes sense to move the dual voltage supply to the SD-MMC
 card only but this rise some more issues :)

 The card is currently wired to port F which Vcc is internally connected
 together with port B and H where is WiFi SIDO , I2C UARTs etc which will be
 lost if we power with 1.8V, so no go.

 We can swap the SD-MMC and eMMC ports, port F and port C, but in this case
 we will lose the NAND Flash option i.e. the possibility to run Android.

 I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point
 me to some model so we perform test and see if this is really good to have
 feature, or we will cut this and wire 3.3V permanently :)
>>>
>>> I have not tried low voltage SD Cards but...
>>>
>>> Here is a chart of the UHS modes
>>> http://panasonic.net/avc/sdcard/industrial_sd/performance.html
>>>
>>> Here are UHS SD Cards for sale:
>>> http://www.lexar.com/products.html
>>>
>>> I was unaware of 0.4V UHS-II, but Lexar is selling UHS-II cards. Don't
>>> know what supply voltage they need.
>>>
>>> ---
>>>
>>> For eMMC I believe you are looking for:
>>> eMMC 4.5 HS200
>>> eMMC 5.0 HS400
>>
>> A64 only has a eMMC 4.5 controller so forget about HS400.
>
> But both the manual and the data sheet mention eMMC 5.0 and HS400
> explicitly several times.
> So do you have knowledge beyond that?

Searching in the manual for HS400 was a better idea, I tried to search

Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[Andre Przywara]

Hi,

On 20/09/16 15:49, jonsm...@gmail.com wrote:
> On Tue, Sep 20, 2016 at 10:45 AM, jonsm...@gmail.com  
> wrote:
>> On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov  
>> wrote:
>>>
>>>
>>> понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа:

 Hi,

 On 19-09-16 18:07, TsvetanUsunov wrote:
> Hi,
>
> We make our final touch of A64-OLinuXino PCB and there we add option
> eMMC Flash to work on dual voltages 1.8V and 3.3V.
> The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that
> when A64 boots and AXP803 is not initialized it outputs default 0.8V then
> after initialization driver takes care to drive it  1.8V or 3.3V.
> This makes impossible to boot from eMMC which is not good. We now think
> for solution which to drive eMMC at 3.3V initially when AXP803 output is
> below 1.8V but this adds unnecessary hardware complexity.
> For hardware point of view it will be much more simplier if dedigated
> A64 GPIO is used and initially is pulled down and after AXP803 is
> initialized is pulled up.

 Ok, so what your suggesting is:

 axp803-ldo-io1  -\
[mux]---> mmc-supply
 Fixed-3.3v --/  |
  |
  |mux-control
 A64 gpio out/

 Note the above ascii-art requires a fixed-width font.

 With a pull-down (or pull-up) to fix the mux in a certain position when
 the gpio is in tri-state ?

 As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator
 framework should be able to deal with, and in u-boot we can just
 keep things at 3.3v.

> How would you suggest us to implement it? Will this additional GPIO
> create troubles in eMMC driver philosophy?

 For the Linux mmc driver the mmc-supply is abstracted as a regulator,
 and the regulator framework should be able to deal with any setup
 you can come up with.

> For the SDMMC we are still hesitating what to do as we don't know if the
> card which will be inserted will support low voltage and higher speeds at
> all.

 As long as you default to 3.3v then the kernel's sd subsystem can
 dynamically switch voltage (through e.g. the gpio) if the card
 advertises it supports low voltage. Note that you're planning
 the first board to implement this that I know off, so the sunxi-mmc
 kernel driver will need some work to support voltage switching,
 but in the mean time things should work fine at 3.3v.

> Also eMMC Flash and SDMMC card should be driven by separate voltages, as
> they may work in any combinations.

 Ack, right, as said both cards should come up with 3.3v and then
 a new voltage will be negotiated before switching, so this definitely
 needs to be per card.

> This means we need another AXP803 LDO and another GPIO for the SDMMC
> card.

 Right
>>>
>>>
>>> Micron eMMC chips we use do not support higher clock at lower voltage, so
>>> the way we wired the schematic right now makes no much sense.
>>> I check for other vendors but also can't find such eMMC chip, if someone
>>> knows please let us know to investigate more?
>>>
>>> So in this case makes sense to move the dual voltage supply to the SD-MMC
>>> card only but this rise some more issues :)
>>>
>>> The card is currently wired to port F which Vcc is internally connected
>>> together with port B and H where is WiFi SIDO , I2C UARTs etc which will be
>>> lost if we power with 1.8V, so no go.
>>>
>>> We can swap the SD-MMC and eMMC ports, port F and port C, but in this case
>>> we will lose the NAND Flash option i.e. the possibility to run Android.
>>>
>>> I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point
>>> me to some model so we perform test and see if this is really good to have
>>> feature, or we will cut this and wire 3.3V permanently :)
>>
>> I have not tried low voltage SD Cards but...
>>
>> Here is a chart of the UHS modes
>> http://panasonic.net/avc/sdcard/industrial_sd/performance.html
>>
>> Here are UHS SD Cards for sale:
>> http://www.lexar.com/products.html
>>
>> I was unaware of 0.4V UHS-II, but Lexar is selling UHS-II cards. Don't
>> know what supply voltage they need.
>>
>> ---
>>
>> For eMMC I believe you are looking for:
>> eMMC 4.5 HS200
>> eMMC 5.0 HS400
> 
> A64 only has a eMMC 4.5 controller so forget about HS400.

But both the manual and the data sheet mention eMMC 5.0 and HS400
explicitly several times.
So do you have knowledge beyond that?

Cheers,
Andre.

>>
>> Kingston sells these, I think Samsung does too.
>> http://www.kingston.com/us/embedded/emmc
>>
>> They come in wide temp
>> https://media.kingston.com/pdfs/emmc/i_temp_eMMC_Product_Flyer.pdf
>>
>> About $5 for 4GB from US distributors, so probably $3 

Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[jonsm...@gmail.com]

On Tue, Sep 20, 2016 at 10:45 AM, jonsm...@gmail.com  wrote:
> On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov  
> wrote:
>>
>>
>> понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа:
>>>
>>> Hi,
>>>
>>> On 19-09-16 18:07, TsvetanUsunov wrote:
>>> > Hi,
>>> >
>>> > We make our final touch of A64-OLinuXino PCB and there we add option
>>> > eMMC Flash to work on dual voltages 1.8V and 3.3V.
>>> > The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that
>>> > when A64 boots and AXP803 is not initialized it outputs default 0.8V then
>>> > after initialization driver takes care to drive it  1.8V or 3.3V.
>>> > This makes impossible to boot from eMMC which is not good. We now think
>>> > for solution which to drive eMMC at 3.3V initially when AXP803 output is
>>> > below 1.8V but this adds unnecessary hardware complexity.
>>> > For hardware point of view it will be much more simplier if dedigated
>>> > A64 GPIO is used and initially is pulled down and after AXP803 is
>>> > initialized is pulled up.
>>>
>>> Ok, so what your suggesting is:
>>>
>>> axp803-ldo-io1  -\
>>>[mux]---> mmc-supply
>>> Fixed-3.3v --/  |
>>>  |
>>>  |mux-control
>>> A64 gpio out/
>>>
>>> Note the above ascii-art requires a fixed-width font.
>>>
>>> With a pull-down (or pull-up) to fix the mux in a certain position when
>>> the gpio is in tri-state ?
>>>
>>> As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator
>>> framework should be able to deal with, and in u-boot we can just
>>> keep things at 3.3v.
>>>
>>> > How would you suggest us to implement it? Will this additional GPIO
>>> > create troubles in eMMC driver philosophy?
>>>
>>> For the Linux mmc driver the mmc-supply is abstracted as a regulator,
>>> and the regulator framework should be able to deal with any setup
>>> you can come up with.
>>>
>>> > For the SDMMC we are still hesitating what to do as we don't know if the
>>> > card which will be inserted will support low voltage and higher speeds at
>>> > all.
>>>
>>> As long as you default to 3.3v then the kernel's sd subsystem can
>>> dynamically switch voltage (through e.g. the gpio) if the card
>>> advertises it supports low voltage. Note that you're planning
>>> the first board to implement this that I know off, so the sunxi-mmc
>>> kernel driver will need some work to support voltage switching,
>>> but in the mean time things should work fine at 3.3v.
>>>
>>> > Also eMMC Flash and SDMMC card should be driven by separate voltages, as
>>> > they may work in any combinations.
>>>
>>> Ack, right, as said both cards should come up with 3.3v and then
>>> a new voltage will be negotiated before switching, so this definitely
>>> needs to be per card.
>>>
>>> > This means we need another AXP803 LDO and another GPIO for the SDMMC
>>> > card.
>>>
>>> Right
>>
>>
>> Micron eMMC chips we use do not support higher clock at lower voltage, so
>> the way we wired the schematic right now makes no much sense.
>> I check for other vendors but also can't find such eMMC chip, if someone
>> knows please let us know to investigate more?
>>
>> So in this case makes sense to move the dual voltage supply to the SD-MMC
>> card only but this rise some more issues :)
>>
>> The card is currently wired to port F which Vcc is internally connected
>> together with port B and H where is WiFi SIDO , I2C UARTs etc which will be
>> lost if we power with 1.8V, so no go.
>>
>> We can swap the SD-MMC and eMMC ports, port F and port C, but in this case
>> we will lose the NAND Flash option i.e. the possibility to run Android.
>>
>> I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point
>> me to some model so we perform test and see if this is really good to have
>> feature, or we will cut this and wire 3.3V permanently :)
>
> I have not tried low voltage SD Cards but...
>
> Here is a chart of the UHS modes
> http://panasonic.net/avc/sdcard/industrial_sd/performance.html
>
> Here are UHS SD Cards for sale:
> http://www.lexar.com/products.html
>
> I was unaware of 0.4V UHS-II, but Lexar is selling UHS-II cards. Don't
> know what supply voltage they need.
>
> ---
>
> For eMMC I believe you are looking for:
> eMMC 4.5 HS200
> eMMC 5.0 HS400

A64 only has a eMMC 4.5 controller so forget about HS400.


>
> Kingston sells these, I think Samsung does too.
> http://www.kingston.com/us/embedded/emmc
>
> They come in wide temp
> https://media.kingston.com/pdfs/emmc/i_temp_eMMC_Product_Flyer.pdf
>
> About $5 for 4GB from US distributors, so probably $3 from Chinese one.
> Random check of similar Kingston part from Chinese supplier - $3.38
>
> Support for HS200/HS400 is already in kernel so someone is using it.
>
>>
>> Tsvetan
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "linux-sunxi" group.
>> To 

Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[jonsm...@gmail.com]

On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov  wrote:
>
>
> понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа:
>>
>> Hi,
>>
>> On 19-09-16 18:07, TsvetanUsunov wrote:
>> > Hi,
>> >
>> > We make our final touch of A64-OLinuXino PCB and there we add option
>> > eMMC Flash to work on dual voltages 1.8V and 3.3V.
>> > The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that
>> > when A64 boots and AXP803 is not initialized it outputs default 0.8V then
>> > after initialization driver takes care to drive it  1.8V or 3.3V.
>> > This makes impossible to boot from eMMC which is not good. We now think
>> > for solution which to drive eMMC at 3.3V initially when AXP803 output is
>> > below 1.8V but this adds unnecessary hardware complexity.
>> > For hardware point of view it will be much more simplier if dedigated
>> > A64 GPIO is used and initially is pulled down and after AXP803 is
>> > initialized is pulled up.
>>
>> Ok, so what your suggesting is:
>>
>> axp803-ldo-io1  -\
>>[mux]---> mmc-supply
>> Fixed-3.3v --/  |
>>  |
>>  |mux-control
>> A64 gpio out/
>>
>> Note the above ascii-art requires a fixed-width font.
>>
>> With a pull-down (or pull-up) to fix the mux in a certain position when
>> the gpio is in tri-state ?
>>
>> As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator
>> framework should be able to deal with, and in u-boot we can just
>> keep things at 3.3v.
>>
>> > How would you suggest us to implement it? Will this additional GPIO
>> > create troubles in eMMC driver philosophy?
>>
>> For the Linux mmc driver the mmc-supply is abstracted as a regulator,
>> and the regulator framework should be able to deal with any setup
>> you can come up with.
>>
>> > For the SDMMC we are still hesitating what to do as we don't know if the
>> > card which will be inserted will support low voltage and higher speeds at
>> > all.
>>
>> As long as you default to 3.3v then the kernel's sd subsystem can
>> dynamically switch voltage (through e.g. the gpio) if the card
>> advertises it supports low voltage. Note that you're planning
>> the first board to implement this that I know off, so the sunxi-mmc
>> kernel driver will need some work to support voltage switching,
>> but in the mean time things should work fine at 3.3v.
>>
>> > Also eMMC Flash and SDMMC card should be driven by separate voltages, as
>> > they may work in any combinations.
>>
>> Ack, right, as said both cards should come up with 3.3v and then
>> a new voltage will be negotiated before switching, so this definitely
>> needs to be per card.
>>
>> > This means we need another AXP803 LDO and another GPIO for the SDMMC
>> > card.
>>
>> Right
>
>
> Micron eMMC chips we use do not support higher clock at lower voltage, so
> the way we wired the schematic right now makes no much sense.
> I check for other vendors but also can't find such eMMC chip, if someone
> knows please let us know to investigate more?
>
> So in this case makes sense to move the dual voltage supply to the SD-MMC
> card only but this rise some more issues :)
>
> The card is currently wired to port F which Vcc is internally connected
> together with port B and H where is WiFi SIDO , I2C UARTs etc which will be
> lost if we power with 1.8V, so no go.
>
> We can swap the SD-MMC and eMMC ports, port F and port C, but in this case
> we will lose the NAND Flash option i.e. the possibility to run Android.
>
> I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point
> me to some model so we perform test and see if this is really good to have
> feature, or we will cut this and wire 3.3V permanently :)

I have not tried low voltage SD Cards but...

Here is a chart of the UHS modes
http://panasonic.net/avc/sdcard/industrial_sd/performance.html

Here are UHS SD Cards for sale:
http://www.lexar.com/products.html

I was unaware of 0.4V UHS-II, but Lexar is selling UHS-II cards. Don't
know what supply voltage they need.

---

For eMMC I believe you are looking for:
eMMC 4.5 HS200
eMMC 5.0 HS400

Kingston sells these, I think Samsung does too.
http://www.kingston.com/us/embedded/emmc

They come in wide temp
https://media.kingston.com/pdfs/emmc/i_temp_eMMC_Product_Flyer.pdf

About $5 for 4GB from US distributors, so probably $3 from Chinese one.
Random check of similar Kingston part from Chinese supplier - $3.38

Support for HS200/HS400 is already in kernel so someone is using it.

>
> Tsvetan
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.



-- 
Jon Smirl
jonsm...@gmail.com

-- 
You received this message because you are subscribed to the Google 

Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[TsvetanUsunov]

понеделник, 19 септември 2016 г., 20:06:13 UTC+3, Hans de Goede написа:
>
> Hi, 
>
> On 19-09-16 18:07, TsvetanUsunov wrote: 
> > Hi, 
> > 
> > We make our final touch of A64-OLinuXino PCB and there we add option 
> eMMC Flash to work on dual voltages 1.8V and 3.3V. 
> > The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that 
> when A64 boots and AXP803 is not initialized it outputs default 0.8V then 
> after initialization driver takes care to drive it  1.8V or 3.3V. 
> > This makes impossible to boot from eMMC which is not good. We now think 
> for solution which to drive eMMC at 3.3V initially when AXP803 output is 
> below 1.8V but this adds unnecessary hardware complexity. 
> > For hardware point of view it will be much more simplier if dedigated 
> A64 GPIO is used and initially is pulled down and after AXP803 is 
> initialized is pulled up. 
>
> Ok, so what your suggesting is: 
>
> axp803-ldo-io1  -\ 
>[mux]---> mmc-supply 
> Fixed-3.3v --/  | 
>  | 
>  |mux-control 
> A64 gpio out/ 
>
> Note the above ascii-art requires a fixed-width font. 
>
> With a pull-down (or pull-up) to fix the mux in a certain position when 
> the gpio is in tri-state ? 
>
> As long as we pin the axp803-ldo-io1 at 1.8v then the Linux regulator 
> framework should be able to deal with, and in u-boot we can just 
> keep things at 3.3v. 
>
> > How would you suggest us to implement it? Will this additional GPIO 
> create troubles in eMMC driver philosophy? 
>
> For the Linux mmc driver the mmc-supply is abstracted as a regulator, 
> and the regulator framework should be able to deal with any setup 
> you can come up with. 
>
> > For the SDMMC we are still hesitating what to do as we don't know if the 
> card which will be inserted will support low voltage and higher speeds at 
> all. 
>
> As long as you default to 3.3v then the kernel's sd subsystem can 
> dynamically switch voltage (through e.g. the gpio) if the card 
> advertises it supports low voltage. Note that you're planning 
> the first board to implement this that I know off, so the sunxi-mmc 
> kernel driver will need some work to support voltage switching, 
> but in the mean time things should work fine at 3.3v. 
>
> > Also eMMC Flash and SDMMC card should be driven by separate voltages, as 
> they may work in any combinations. 
>
> Ack, right, as said both cards should come up with 3.3v and then 
> a new voltage will be negotiated before switching, so this definitely 
> needs to be per card. 
>
> > This means we need another AXP803 LDO and another GPIO for the SDMMC 
> card. 
>
> Right


Micron eMMC chips we use do not support higher clock at lower voltage, so 
the way we wired the schematic right now makes no much sense. 
I check for other vendors but also can't find such eMMC chip, if someone 
knows please let us know to investigate more?

So in this case makes sense to move the dual voltage supply to the SD-MMC 
card only but this rise some more issues :)

The card is currently wired to port F which Vcc is internally connected 
together with port B and H where is WiFi SIDO , I2C UARTs etc which will be 
lost if we power with 1.8V, so no go. 

We can swap the SD-MMC and eMMC ports, port F and port C, but in this case 
we will lose the NAND Flash option i.e. the possibility to run Android.

I still can't find SD-MMC card which to work on 1.8 and 3.3V can you point 
me to some model so we perform test and see if this is really good to have 
feature, or we will cut this and wire 3.3V permanently :)

Tsvetan 

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Re: [linux-sunxi] Dual voltage SDMMC/eMMC on A64

[jonsm...@gmail.com]

On Mon, Sep 19, 2016 at 12:07 PM, TsvetanUsunov  wrote:
> Hi,
>
> We make our final touch of A64-OLinuXino PCB and there we add option eMMC
> Flash to work on dual voltages 1.8V and 3.3V.
> The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that when
> A64 boots and AXP803 is not initialized it outputs default 0.8V then after
> initialization driver takes care to drive it  1.8V or 3.3V.
> This makes impossible to boot from eMMC which is not good. We now think for
> solution which to drive eMMC at 3.3V initially when AXP803 output is below
> 1.8V but this adds unnecessary hardware complexity.
> For hardware point of view it will be much more simplier if dedigated A64
> GPIO is used and initially is pulled down and after AXP803 is initialized is
> pulled up.
> How would you suggest us to implement it? Will this additional GPIO create
> troubles in eMMC driver philosophy?
> For the SDMMC we are still hesitating what to do as we don't know if the
> card which will be inserted will support low voltage and higher speeds at
> all. Also eMMC Flash and SDMMC card should be driven by separate voltages,
> as they may work in any combinations.
> This means we need another AXP803 LDO and another GPIO for the SDMMC card.
>
> By the way the current eMMC from Micron we use has 11MB Write speed no
> matter what is the voltage and this is written in the datasheet, so maybe we
> should switch and add this dual voltage to the SD MMC where someone could
> use SD MMC card supporting higher clocks?

Does eMMC exist with the higher speed 1.8V option?

I know some SD Cards support it.

>
> I would love to hear your opinion.
>
> Tsvetan
>
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-- 
Jon Smirl
jonsm...@gmail.com

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