topic Re: read/write reg in i.MX Processors

read/write reg

rainho — Fri, 27 Oct 2023 03:09:22 GMT

I wrote the device driver code for the SPI slave device mounted under the spi device tree node, and it works normally. But now I have a requirement for fast communication. I do not use APIs such as kernel spi_sync during transmission, and choose to directly operate the SPI register. I found that it will cause the kernel to hang directly. When matching the device driver, I used ioremap again to obtain the starting virtual address of the hardware SPI, and then directly operated the offset (register) of the starting address in the device driver file, but the kernel hung. What is this? The reason? Is it because Ioremap uses the same SPI memory twice? Or is there a conflict with spi_imx.c when using functions such as readl?
Please answer it. Thank you!

Re: read/write reg

Zhiming_Liu — Mon, 30 Oct 2023 02:39:20 GMT

Recommend you use regmap framework to operate regs

Re: read/write reg

rainho — Mon, 30 Oct 2023 03:56:06 GMT

thanks for the reply!
I probably know about the regmap operation, but I'm not sure whether it is a safe operation, or whether it can be used directly in interrupts?

Re: read/write reg

Zhiming_Liu — Wed, 01 Nov 2023 00:27:30 GMT

Avoid using ioremap, regmap is more safety.