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BOOT_CFG1[3:2] and SD card working mode

Question asked by Zongbiao Liao on Apr 4, 2016
Latest reply on Apr 14, 2016 by Zongbiao Liao

Hello Community

 

I did a test as bellow:

--Environment

(1)i.MX6QSabreAI CPU1 board.

(2)Yocto3.14.28.

(3)A SanDisk SD card with SDR104 mode supported.

 

--Steps

(1)Boot from SD3.

(2)Set BOOT_CFG1[3:2](that is bit[10:9] of S1 on sabreai CPU board) and test read speed of SD card inserted to SD3 slot.

 

--Results

(1)BOOT_CFG1[3:2] is set to 00'b

Kernel log is 'mmc2: new ultra high speed SDR104 SDHC card at address aaaa'.

And the read speed is 50M/S

 

(2)BOOT_CFG1[3:2] is set to 01'b

Kernel log is 'mmc2: new ultra high speed SDR104 SDHC card at address aaaa'.

And the read speed is 50M/S

 

(3)BOOT_CFG1[3:2] is set to 10'b

Kernel log is 'mmc2: new high speed SDHC card at address aaaa'.

And the read speed is 18M/S

 

(4)BOOT_CFG1[3:2] is set to 11'b

Kernel log is 'mmc2: new high speed SDHC card at address aaaa'.

And the read speed is 18M/S

 

Questions

(1)According to Table 8-14. USDHC Boot eFUSE Descriptions,for SD card BOOT_CFG1[3:2] means:

0x - High/Normal

10 - SDR50

11 - SDR104

 

My test results are not matching Table 8-14 and it just oppsites to Table 8-14.

Please tell me the reason.

 

Best Regards!

ZongbiaoLiao

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