Linux/WL1807MOD: Linux command to read SDIO frequency

Johncy Bennette

Expert 1180 points

Part Number: WL1807MOD

Tool/software: Linux

Hi,

How do I read the read the SDIO frequency in linux in the target? We are using WL1807.

Regards,

Johncy.

over 8 years ago

0 Vihang Parmar over 8 years ago

TI__Mastermind 29311 points

Hi,

Your query has been assigned to a relevant expert. We will get back to you soon.

Best regards,
Vihang

0 Eyal Reizer over 8 years ago

TI__Mastermind 20285 points

See the following example:

root@am437x-evm:~# cat /sys/kernel/debug/mmc1/ios
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: 2 (sd high-speed)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)
root@am437x-evm:~#

0 Johncy Bennette over 8 years ago in reply to Eyal Reizer

Expert 1180 points

Thanks Eyal.

With frequency configured to 40 MHz,

cat /sys/kernel/debug/mmc1/ios
clock: 40000000 Hz
actual clock: 39600000 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: 2 (sd high-speed)
signal voltage: 0 (3.30 V)

I changed the frequency to 20 MHz in dts file and generated the build, with that
cat /sys/kernel/debug/mmc1/ios
clock: 20000000 Hz
actual clock: 19800000 Hz
vdd: 7 (1.65 - 1.95 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 2 (sd high-speed)
signal voltage: 0 (3.30 V)

Why the vdd value is changing?

Regards,
Johncy

0 Eyal Reizer over 8 years ago in reply to Johncy Bennette

TI__Mastermind 20285 points

Hi Johncy,

I am not sure, this is probably some stupid display bug in the host mmc driver.
You don't really have to care about this value. It is driven by a hardware voltage supply anyway.

Best Regards,
Eyal

Wi-Fi

Wi-Fi forum

Linux/WL1807MOD: Linux command to read SDIO frequency