00:25 <brads> On the odroid C2 I was able to get sd UHS-I modes sd-uhs-sdr25, sd-uhs-sdr50 by adding the entries to device tree, for sd-uhs-sdr104 I also needed to increase the max clock frequency to 200000000. It seems to work well from initial test. 87Mb/s on sequential read test.

00:29 <brads> sorry 82MB/s

02:55 <wens> nice

03:08 <wens> lvrp16: narmstrong: looks like aml-s905x-cc / Le Potato should be able to do the same?

03:09 <lvrp16> wens: jbrunet tested it extensively and the only stable frequency is 100MHz. any higher the waveform becomes deformed.

03:10 <lvrp16> capacitance is an issue and it seems s905x doesn't have the ability to drive it at 200mhz

03:14 <wens> still, Le Potato dts only has cap-sd-highspeed; even just adding sd-uhs-sdr25 and sd-uhs-sdr50 would be a performance win

03:16 <brads> does the board have voltage select for the 1.8 volt IO?

03:17 <wens> looks like it does

03:17 <wens> I assume it might be part of the reference design from Amlogic

03:18 <brads> yes you are probably right

03:20 <brads> Will do some more tests and see if I can find any issues on the Odroid.

03:20 <wens> I only have the nanopi k2, which seems to have it enabled for quite some time

04:18 <lvrp16> S905 can do UHS, S905X cannot

04:18 <lvrp16> Le Potato has the voltage switch but no power off

04:19 <lvrp16> you need an IO for power off

04:19 <lvrp16> power cycle is necessary to restore normal functioning per SD spec

04:19 <lvrp16> on Samsung cards, without power cycle the SD card will not work on reboot

04:37 <wens> lvrp16: looks like the nanopi-k2 doesn't support power cycling the SD card either lol

04:38 <lvrp16> wens: the reference design doesn't include it to save on IO pins and the considered use case is a TV box so they don't assume it to be a storage device

04:38 <lvrp16> wens: root storage device. this will be remedied in le potato plus or whatever the next gen libre computer s905x board is called

07:23 <brads> thanks for the info @lvrp16 I was going to setup a better circuit for the sdio port on the C2 as well (for my board with a broken sd card connector), ill try to include power off control as well.

07:24 <brads> The card have success with SDR104 is Sandisk Extreme Pro 64Gb A2

07:36 <wens> brads: I suppose without card power control, the board would be stuck in UHS / 1.8V modes after reboot, and the BROM would have no way to talk to it

17:15 <lvrp16> brads: jbrunet figured all of this out :)

17:16 <lvrp16> wens: yep some cards work ok but samsung ones will just die. others will not tune for uhs on second boot. sandisk extreme pro seems to be the only ones that can go back to uhs in my testing.