topic [i.mx8mp] Unable to access multiple nand flash on u-boot in i.MX Processors

[i.mx8mp] Unable to access multiple nand flash on u-boot

junya — Thu, 31 Aug 2023 03:04:20 GMT

I have a custom board with a i.MX8MP and a KIOKXIA TH58NVG4S0HTAK0 which should be used as boot device.

Boot device : NAND FLASH 2GB (2 chip select, 1chip select is 1GB)

　 (Image size to be written is 1.6 GB)

brunch：imx-linux-hardknott

manifesto：imx-5.10.35 2.0.0.xml

DISTRO：fsl-imx-wayland

MACHINE：mx8mpevk

Probably succeeded until u-boot was booted.

Reads and writes to NAND located in NAND_CE0 are successful.

However, CE1 fails...

The log of the success and failure is attached.

Am I doing something wrong with the confirmation?

Best regards.

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

junya — Thu, 31 Aug 2023 11:55:03 GMT

We found that there is a difference in AC characteristics when leading to CE0 and when leading to CE1.

(Image attached.)

CE1 is not working properly after sending the second cycle 30h of read operation.
Before the ready pin goes High, the CE1 pin goes Low and the read operation is started.
CE0 looks correct.

Therefore, I assume that the AC characteristic settings of CE0 and CE1 are different in the U-boot.

But I don't know how to fix it.

I need to know how to fix it.

Best regards.

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

Sanket_Parekh — Fri, 01 Sep 2023 06:46:19 GMT

Hi @junya,

I hope you are doing well.

I have responded to your query in [i.mx8mp] Boot from nand flash.

Have you disabled internal pull-up in u-boot dts?

Please try in the kernel to see if CE1 works or not.

Thanks & Regards,
Sanket Parekh

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

junya — Fri, 01 Sep 2023 07:39:38 GMT

Hi, @Sanket_Parekh .

Thank you for your help.

Have you disabled internal pull-up in u-boot dts?

Yes, i had already disabled internal pull. ( External pull-up are implemented.)

What do you think about the attached CE1 waveform?
Read accesses are initiated even though the memory is busy.

Best regards.

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

koichi_arima — Mon, 04 Sep 2023 10:48:31 GMT

Dear Sanket-san
This problem seems to be a problem with Uboot settings. Is it possible to share code, including settings such as defconfig of multiple NANDs verified by NXP, in order to speed up problem fix?

Thanks

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

Sanket_Parekh — Tue, 05 Sep 2023 09:34:16 GMT

Hi @junya,

I hope you are doing well.

It seems that Multiple chipselect or nand device support is not available in the nand driver in U-boot.

One needs to set DECOUPLE_CS to decouple Chip Select from the DMA Channel. to enable multiple Chip Select.

It was fixed in the kernel with the below commit.
mtd: rawnand: gpmi: Fix the driver only sense CS0 R/B issue

One needs to make changes to u-boot for multiple CS. Please refer to the below patch.

[U-Boot] mtd: nand: mxs: Add support for multiple NAND chips

I hope it helps!

Thanks & Regards,
Sanket Parekh

Re: [i.mx8mp] Unable to access multiple nand flash on u-boot

junya — Tue, 05 Sep 2023 10:58:29 GMT

Hi, @Sanket_Parekh san.

Thank you very much!!

After applying the patch of u-boot you shared with me, this problem was resolved.