imx6sx ; How does Linux change the BCLK frequency ?

[bap3ball]

I am setting the BCLK to continuous mode in u-boot, and setting the EIM_SLOW_PODF bits in CSCMR1 to get a 66Mhz external BCLK frequency. When I stop u-boot from booting Linux, then I see the expected 66Mhz clock.

However, once Linux boots the clock gets changed to 133Mhz. Is this controlled by the device tree?

If so, can someone provide the required change to reduce this frequency?

Thanks

[igorpadykov]

Hi Bruce

please look at linux documentation../bindings/bus/imx-weim.txt how to set CSxGCR1 :


linux-2.6-imx.git - Freescale i.MX Linux Tree

Best regards

igor

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[bap3ball]

Ok, but I need to run in continuous BCLK which I believe means the BCD in CSxGCR1 must be set to 0.

When using continuous BCLK mode, how is the BCLK frequency changed? Is there some control of the EIM_WCR in a device tree?

It looks to me like either setting WCR[GBCD] and WCR[BCM=1] or changing the CSCMR1(slow_podf) could work. Are one of those the preferred method for change BCLK frequency in continuous mode?

If so, how are those changed in a device tree?

[BiyongSUN]

You mentioned is SSI or SAI interface?

[igorpadykov]

all CSxGCR can be changed by property: "fsl,weim-cs-timing",

EIM_WCR seems can not be changed.

Regarding "how"s  for continuous BCLK, suggest to create new thread.