topic Re: iMX6SX PXP Register Access in i.MX Processors

iMX6SX PXP Register Access

SamM — Mon, 31 Mar 2025 15:29:45 GMT

I am trying to set the PXP CSC2 registers in an IMX6SX, similar to this post.

To begin with I simply attempt to read the PXP_CTRL register at 0x2218000
My code looks like this:

import ctypes import mmap def read_word(address): with open('/dev/mem', 'rb') as f: mem = mmap.mmap(f.fileno(), mmap.PAGESIZE, mmap.MAP_SHARED, mmap.PROT_READ, offset=address&~(mmap.PAGESIZE-1)) s = ctypes.c_uint32.from_buffer_copy(mem, address&(mmap.PAGESIZE-1)) mem.close() return s print(read_word(0x2218000))

The result is that the kernel hangs with no error.

I am able to read other registers (for example GPIOs at 0x20E0014).

I have the PXP enabled and clocks configured in the device tree:

pxp: pxp@2218000 {
compatible = "fsl,imx6sx-pxp-dma", "fsl,imx6sl-pxp-dma", "fsl,imx6dl-pxp-dma";
reg = <0x02218000 0x4000>;
interrupts = <GIC_SPI 8 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6SX_CLK_PXP_AXI>,
<&clks IMX6SX_CLK_DISPLAY_AXI>;
clock-names = "pxp-axi", "disp-axi";
power-domains = <&pd_disp>;
status = "okay";
};

Is there anything else I need to set up before I can read/set the PXP registers?

Re: iMX6SX PXP Register Access

JosephAtNXP — Mon, 31 Mar 2025 19:52:46 GMT

Hi,

Thank you for your interest in NXP Semiconductor products,

Could you try with memtool command?

Regards

Re: iMX6SX PXP Register Access

SamM — Tue, 01 Apr 2025 08:14:30 GMT

I added memtool to my image and tried the command:

memtool -8 2218000 1

The resulting output is:

E
Reading 0x1 count starting at ad

And then the kernel hangs again.

I also tried with -16 and tried reading a couple of the other PXP registers.
The result was the same in all cases (even the same truncation of the output)

At least it seems like my code was probably fine, but there must be something I need to set up to enable the PXP module? Any ideas?

Re: iMX6SX PXP Register Access

jamesbone — Wed, 02 Apr 2025 15:35:15 GMT

Hello @SamM ,

Can you please share more details about your project, are you using your own design with the i.MX6SX, or which board are you using? how much DDR memory has it? which BSP and version are you using?

Any other details that can help us to narrow the problem, like is there any warning or error during the boot up? if you can share a log, would be good to see if there is anything else that maybe pointing what would be the issue.

Right now, I think it is a RAM issue, but maybe something else it is consuming your free memory or any other peripheral it is creating a big load to the memory.

Re: iMX6SX PXP Register Access

SamM — Wed, 02 Apr 2025 16:40:51 GMT

Hi James,

Thanks for getting back to me.

It is a COM board produced by embedded artists
It has 1GB DDR3 (and free says 741MB is currently available)

I'm using a custom BSP provided by embedded artists (slightly modified by me to adjust lvds device timings). It is on kernel version 6.6 and uses meta-imx rel_imx_6.6.23_2.0.0

It seems reasonable to test with the NXP BSP. I'll grab the 6.6.23 BSP and re-test with that.

Output from dmsg attached

Re: iMX6SX PXP Register Access

SamM — Thu, 03 Apr 2025 08:35:45 GMT

@jamesboneI have just tested an iMX6ULL-14x14-evk that I have on hand, with the NXP V6.6.52-2.2.0 BSP.

I get the same result reading the PXP_HW_PXP_CSC2_CTRL register on that board

memtool -16 21CC1D0 1

Output is truncated and the kernel hangs

I also noted that the pxp_test.out unit test doesn't appear to do anything and the mxc_fb_test.out unit test hangs part way through.

Re: iMX6SX PXP Register Access

SamM — Thu, 03 Apr 2025 08:48:07 GMT

Sorry, mxc_fb_test.out does eventually terminate but it segfaults.

dmesg output from that board attached.

Re: iMX6SX PXP Register Access

jamesbone — Thu, 03 Apr 2025 15:39:20 GMT

@JosephAtNXP , can you please try to reproduced the issue from @SamM , in the NXP board.

Thanks

Re: iMX6SX PXP Register Access

JosephAtNXP — Thu, 03 Apr 2025 22:57:04 GMT

Hi @jamesbone @SamM,

I can reproduce on i.MX6UL devices too, we are reviewing this issue and will provide feedback about the workarounds ASAP,

Regards

Re: iMX6SX PXP Register Access

SamM — Mon, 07 Apr 2025 15:02:53 GMT

Hi @JosephAtNXP

Is there any update on this?

Re: iMX6SX PXP Register Access

JosephAtNXP — Mon, 07 Apr 2025 16:04:17 GMT

Hi,

Please update the following:

cat /sys/kernel/debug/clk/clk_summary | grep pxp

Regards,

Re: iMX6SX PXP Register Access

SamM — Mon, 07 Apr 2025 16:24:42 GMT

Here is the output of

cat /sys/kernel/debug/clk/clk_summary | grep pxp

On the iMX6ULL14x14-evk

Re: iMX6SX PXP Register Access

SamM — Wed, 09 Apr 2025 16:12:54 GMT

@JosephAtNXP

Do you have any more information for me?

Re: iMX6SX PXP Register Access

SamM — Mon, 14 Apr 2025 07:34:30 GMT

Morning @JosephAtNXP

Do you have any more details for me this week?

Re: iMX6SX PXP Register Access

JosephAtNXP — Mon, 14 Apr 2025 21:26:45 GMT

Hi,

I'm still waiting for feedback from the team,

Regards

Re: iMX6SX PXP Register Access

JosephAtNXP — Tue, 15 Apr 2025 17:28:06 GMT

Hi,

The clocks are not enabled and registers cannot be accessed as a consequence, team is reviewing clock enabling.

Regards

Re: iMX6SX PXP Register Access

JosephAtNXP — Wed, 16 Apr 2025 20:36:22 GMT

In PXP driver, runtime PM will dynamic open/close clock. For workaround, you can comment out 'clk_unprepare' in PXP relating driver.