AnsweredAssumed Answered

SDHC very slow (300-600 KB/s) on i.MX25 board

Question asked by Stefan Koch on Dec 3, 2012
Latest reply on Jan 25, 2017 by Maxim Kochetkov



I have ported linux-3.7-rc4 to a board with i.MX257 CPU.

As distribution I use Debian squeeze.

Booting time (with Xorg and IceWM) is different with different SD-Cards.

Boot time with 2GB Standard micro SD-Card: over 2:30 minutes

Boot time with 4GB Class 10 micro SDHC: 1:40 minutes

Boot time with 8GB UHS-1 micro SDHC: 1:15 minutes

Boot time with NFS (Network without SD/SDHC): 40 seconds


Starting applications is faster with NFS as with SD/SDHC.

At SD/SDHC linux is system is waiting a lot of time.

Then CPU can not run at 100% usage, so system is not so fast as possible.


Tests with dd give ratings from a. e. 300 KB/s (this could be a Class 10 card).


But there is a relationship with slower and faster SD/SDHC-cards:

A UHS card works faster than a class 10 card an so on.

And a Standard 2GB SD card is the slowest.

But the Standard 2GB SC card works with a card reader connected to an Notebook faster than the UHS-1 Card in the imx257 Target system with imx integrated SDHC controller.


How to solve this problem?

Is it a driver issue?




Stefan Koch