IMX8MP reading ISI registers from m7 causes hang issue

[Khai]

Hi everyone,

Im trying to read ISI register from m7 side in imx8mp. When using u-boot to run the m7 image, I can have full access to ISI peripheral without problem. But when linux OS boot, both m7 and linux (a53) hang immediately when m7 side tries to read the ISI registers for the first time. 

I have configured the RDC to assign ISI to m7 (domain 1) but the problem still occurs. 
Can I access ISI registers independently from M7 side when linux boot up or it must be sticked to MIPI CSI, ISP or MEDIA block?

Are there any permission controls other than RDC for assigning peripherals to M7 core?

Best regards,

[Zhiming_Liu]

Hi @Khai 

If you want to share ISI between M and A core, you need use SEMA module to access, the SDK contain these API, you may find reference in SDK(boards\evkmimx8mp\driver_examples\rdc).

[Khai]

Hi @Zhiming_Liu ,

Thank you for your quick supports!

I forgot to mention that the ISI node is deleted from devicetree, so it is not used by linux kernel.

I also set the ISI's corresponding MDA6 and PDAP32 to m7 (domain1) using RDC module and SEMA module.

From m7 firmware, I just simply read the ISI registers once then the Linux and M7 both hang immediately

This problem does not happen in other peripherals such as SPI or PWM

Are there any HW restrictions in using ISI from m7 side?

[Zhiming_Liu]

Hi @Khai 

For Linux side, if we want to use ISI, we need power up ISI in media blk domain, and this step needs us to power up the media block ctl in GPC PGC.

I think you may need power up them in M core. Can you check that?

Best Regards

Zhiming