topic Re: mipi-csi access issue in i.MX Processors

mipi-csi access issue

t-sugiyama — Mon, 27 Apr 2020 05:33:27 GMT

Hello,
I understand the lack of performance of iMX8Mmini's cortex-M4 and dare to access MIPI-CSI and CSI Bridge with cortex-M4.
I actually made a program to access MIPI-CSI and CSI Bridge registers with cortex-M4, and confirmed that the camera data was acquired.
However, the process succeeds when I run only the cortex-M4 program from u-boot, but when IMX-Linux is run in parallel, when the cortex-M4 program accesses the MIPI-CSI register. It freezes.

I intend to edit the device tree of IMX-Linux and delete the nodes related to MIPI-CSI and CSI Bridge. Is it still insufficient?

Or is there a mechanism that the register access from the cortex-M4 cannot be done when the cortex-A53 operates as the SoC specifications?

IMX-Linux: Rev. L4.14.98_2.3.0, 22 January 2020
Board: 8MMINILPD4-EVK

Attach the used device tree.

Thanks.
Tetsuya.

Re: mipi-csi access issue

igorpadykov — Mon, 27 Apr 2020 10:38:51 GMT

Hi Tetsuya

>I intend to edit the device tree of IMX-Linux and delete the nodes related to

>MIPI-CSI and CSI Bridge. Is it still insufficient?

I believe it is sufficient.

>Or is there a mechanism that the register access from the cortex-M4 cannot be

>done when the cortex-A53 operates as the SoC specifications?

such mechanism is provided using RDC, it is described in sect.3.2 Resource Domain Controller (RDC)

i.MX 8M Mini Applications Processor Reference Manual

Best regards
igor
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Re: mipi-csi access issue

t-sugiyama — Tue, 28 Apr 2020 01:30:56 GMT

Hi igor

Thank you for your consultation.

I tried setting RDC on cortex-M4.
When setting No Read Access except Domain 1 in the register RDC_PDAP34 (CSI), a kernel panic occurred during IMX Linux startup and only IMX Linux stopped.
* (UW) 0x303D0488 = 0x0000000c;

I expect IMX Linux to try to access the CSI.
In this case, do I need to check the kernel source code as well as edit the device tree?

Best regards
Tetsuya

Re: mipi-csi access issue

igorpadykov — Tue, 28 Apr 2020 07:06:45 GMT

Hi Tetsuya

also one can check rdc configuration in

imx8mm_bl31_setup.c\imx8mm\imx\plat - imx-atf - i.MX ARM Trusted firmware

Best regards
igor