SD card reader SD support

Hardware Librem 5
1

Dear @dos
have you know if Librem 5 support: SDR104 mode or any?

Thanks

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2

OK. I can confirm that Librem 5 SOC support SDR104 however i not sure if exist a bottleneck in the Librem 5 scheme.

So i really recommend to use a SDcard U1 V30 A1+ for Librem 5. A1 is first features to manager a operating system. V30 is first feature to manager video writer. U1 is first features to manager Utra High Speed Bus.

So i recommend to use this sdcard ONLY for Librem 5: https://www.raspberrypi.com/documentation/accessories/sd-cards.html

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3

This doesn’t seem to take into account what has been discussed previously: Why is internal card reader so slow? - #6 by Privacy2. Some of the L5 components limit speeds and card standards, so yes, there is a bottleneck.

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4

Yes i remember that thread/post however if the test was on wrong sdcard then the bottleneck may be come from SDcard. I just say.

Of course i will full brakedown to see whats going on.

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5

@JR-Fi I brakedown a little and yes the usb2.0(shame) controller it is the bottleneck for SDR104 via sd-slot however the soc still support it via M.2. :smiling_face_with_tear:

Thank you.

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6

Still breakdown SDR104 until i have it all clear… So yes as what i say Librem 5 soc support SDR104 via sdio v3.0, in fact sdr104 it may in use via WLAN. So what i looking is if we use it a SDR104+A2 SDcard even with the bottleneck, we may have some features like powersave, more speed like 30MBps or 45MBps, and a better .img managements on sdcard.
I just saying… At the moment of the research is in theoretically nothing in testing…

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7

purism@gnu-os:$ sudo hdparm -tT /dev/mmcblk0

/dev/mmcblk0:
Timing cached reads: 1764 MB in 2.00 seconds = 882.26 MB/sec
Timing buffered disk reads: 500 MB in 3.00 seconds = 166.54 MB/sec

root@gnu-os:/sys/kernel/debug# cat mmc*/ios
clock: 200000000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don’t care)
power mode: 2 (on)
bus width: 3 (8 bits)
timing spec: 10 (mmc HS400)
signal voltage: 1 (1.80 V)
driver type: 0 (driver type B)
clock: 50000000 Hz
actual clock: 50000000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don’t care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 6 (sd uhs SDR104)
signal voltage: 1 (1.80 V)
driver type: 0 (driver type B)

Looks really nice overall, so yes i strong recommend a SDR104 SDCard for Librem 5 even over the bottleneck-usb2.0.

Also this confirm that L5 is huge better that PPP o PP.

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