IMX6 uSDHC controller performance

[edison_xu1981]

HI Community,

     I'm testing the uSDHC controller performance on IMX6S demo board

Kernel: 3.10.17

SD card: Transcent 16GB UHS-I 600X TF (max read/write speed 90MB/s)

SD card reader: support USB 3.0

1 Using uSDHC controller

dd if=/dev/mmcblk1 of=/dev/null bs=4096k count=100

100+0 records in

100+0 records out

419430400 bytes (400.0MB) copied, 20.196583 seconds, 19.8MB/s

     The performance is very poor, even lower than 20MB/s, it is far from the speed on the reference manual - Up to 104MB/s

2 Using USB card reader

dd if=/dev/sda of=/dev/null bs=4096k count=100

100+0 records in

100+0 records out

419430400 bytes (400.0MB) copied, 15.732688 seconds, 25.4MB/s

     The IMX6S only support USB2.0 host, so it cannot get the maximum speed, however, the performance is better than uSDHC controller.

     Can IMX expert give explanation on this difference? How to get the best performance of uSDHC controller?         

[igorpadykov]

Hi edison

for UHS-I usage (speed up to 104MB/s) it is necessary to use

uSDHC I/O 1.8V voltage change as it is done on sabre ai schematic

sch-27142 p.6, U508.

Schematics (1)

i.MX6_SABRE_AI_DESIGNFILES

http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-process...

Best regards

igor

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[edison_xu1981]

Hi Igor,

We've made the uSDHC I/O 1.8V voltage changs on our IMX6S board. Unfortunately,  it gets read errors as below with 1.8V voltage, but it works with 3.3V voltage.

What' wrong with it?

U-Boot-V150 > mmc dev 1

mmc1 is current device

U-Boot-V150 > ext2ls mmc 1:1 /boot

<DIR>       1024 .

<DIR>       1024 ..

        15339520 a.tar

           33094 imx6solo_v150.dtb

          201216 tftpd32.exe

          133264 tftpd32.zip

          246916 u-boot.bin

          267396 u-boot.imx

          268420 u-boot.imx.veex

         4585360 uImage

         8552448 v150.cramfs

U-Boot-V150 > ext2load mmc 1:1 $loadaddr /boot/uImage

** ext4fs_devread read error - block

[martinma]

Hi igorpadykov,

We've made the uSDHC I/O 1.8V voltage changs on our IMX6S board. Unfortunately,  it gets read errors as below with 1.8V voltage, but it works with 3.3V voltage.

What' wrong with it?

U-Boot-V150 > mmc dev 1

mmc1 is current device

U-Boot-V150 > ext2ls mmc 1:1 /boot

<DIR>       1024 .

<DIR>       1024 ..

        15339520 a.tar

           33094 imx6solo_v150.dtb

          201216 tftpd32.exe

          133264 tftpd32.zip

          246916 u-boot.bin

          267396 u-boot.imx

          268420 u-boot.imx.veex

         4585360 uImage

         8552448 v150.cramfs

U-Boot-V150 > ext2load mmc 1:1 $loadaddr /boot/uImage

** ext4fs_devread read error - block