Imx8mq - hdmi fails to initialise in u-boot because cmn_ready is not set

[wenyong]

Dear NXP engineers, 

I have a customised board which has the same HDMI design as imx8mq evk board. 

However, in u-boot, it often fails at checking the cmn_ready bit of HDMI's PMA. 

It's in API_AFE_t28hpc_hdmitx.c -> phy_cfg_t28hpc

It will wait for cmn_ready forever. 

If I unplug power and connect power,  u-boot would be able to pass this check. 

If I just reboot the Linux or run reset in u-boot, it would mostly fail here. 

Could you help to explain what is cmn_ready? and in what cases it might fail?

Anything I can check on hardware side?

Thanks,

Wenyong

[wenyong]

Hi @joanxie, 

This issue seems to be power related. 

In u-boot, we don't have PMIC driver configured, our PMIC is on i2c4 and we are still trying to make it work. 

However, we experience i2c4 errors after we enable i2c4 and pmic drivers. 

[joanxie]

when did you get this issue? would you get this issue when you boot up the board first time? HDMI FW loading is done by the ROM, if you use reset, it wouldn't be reload again, and HDMI doesn't support SW reset, I'm not sure how you trigger this issue, for cmn_ready，according to your code, this is set by the bit0 of PMA common control1 register (phy_pma_cmn_ctrl1), and for this bit, means detect the ready signal, Wait for 0th bit to be 1'b1.