Autodetect of SD card speed?

[alampret]

Hello everyone,

one basic question regarding boot_cfg and sd card speed.

The sd card speed is defined by BOOT_CFG parameters.

After successful boot does linux rely on the boot_cfg settings or is sd card speed auto-detected?

As an example, if I specify BOOT_CFG to SDR12 but SD card supports SDR104. Does linux automatically switch to SDR104 or do I need to correctly specify BOOT_CFG?

Thx in advance!

Best regards,

Alexander

[igorpadykov]

Hi Alexander

in general linux should check available speed options and try max. option.

So seems it should try to switch to SDR104, note hardware should support voltage switching

and also dts has options like "pinctrl_usdhc1_200mhz":

linux-imx.git - i.MX Linux Kernel 

Best regards
igor
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