topic Re: sd_clk rate on mmc1 in i.MX Processors

sd_clk rate on mmc1

davesimonson — Tue, 09 Feb 2021 13:28:45 GMT

I have a WL1810 wifi on SD1. The SD_CLK runs at 50MHz in HI-SPEED mode.

I wish to limit this to 25MHz. I cannot find the code where this is set.

Re: sd_clk rate on mmc1

IvanRuiz — Tue, 09 Feb 2021 20:49:35 GMT

Hello,

To change the speed of the MMC, it would be possible through the device tree and the config of the kernel. But for the boot, it will have to be set through a fuse in BOOT_CFG => MMC Speed Mode(CFG[3:2]), where:

00 - Normal

01 - High

Hope it helps!

BR,

Ivan.

Re: sd_clk rate on mmc1

davesimonson — Tue, 09 Feb 2021 22:27:15 GMT

@IvanRuiz Thank you for your help Ivan. It reminded me of things I had forgotten.
I may still need some help.
I have been using a wifi device: TiWi-BLE on this interface for a few years.
I am now using the TI WL1801 on that interface.
The old system used 25MHz HI-SPEED mode, while the new system uses 50MHz.

I am seeing sporadic behavior.
I wish to limit HI-SPEED mode to 25MHz to see what results.
Adding max-frequency = <25000000> to the device tree has no affect.

Thoughts?

Thanks.

Re: sd_clk rate on mmc1

IvanRuiz — Wed, 10 Feb 2021 17:22:05 GMT

Hello,

It might be that your new module does not accept that frequency.

BR,

Ivan.