On Tue, Sep 20, 2016 at 10:45 AM, [email protected] <[email protected]> wrote: > On Tue, Sep 20, 2016 at 10:10 AM, TsvetanUsunov <[email protected]> > 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 unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. > > > > -- > Jon Smirl > [email protected] -- Jon Smirl [email protected] -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
