I.MX8 MMC clock rate and bus-width customisation in Linux

取消
显示结果 
显示  仅  | 搜索替代 
您的意思是: 
已解决

I.MX8 MMC clock rate and bus-width customisation in Linux

跳至解决方案
2,469 次查看
liamjm36
Contributor II

Hey,

I am relatively new to Embedded Linux development but have not been able to find answers elsewhere. 

How can I change the clock speeds and bus width of the mmc device? We are using an SD card multiplexer which has been tested and works when clocked at 16 MHz for SDIO. However I cannot get it to be recognised in Linux. When mounted directly SD cards are recognised. Running the following terminal command I found that the card was being read from a 208 MHz clock. 

/sys/kernel/debug/mmc1# cat clock

 

I would like to be able to lower the maximum MMC clock rates and optionally being able to select 1 bit SDIO instead of 4. 

 

Thanks,

Liam

0 项奖励
回复
1 解答
2,459 次查看
igorpadykov
NXP Employee
NXP Employee
0 项奖励
回复
1 回复
2,460 次查看
igorpadykov
NXP Employee
NXP Employee

Hi Liam

 

one can look at general linux mmc documentation

https://source.codeaurora.org/external/imx/linux-imx/tree/Documentation/devicetree/bindings/mmc/mmc-...

 

Best regards
igor

0 项奖励
回复