i.MX93: FlexSPI Sample Clock Source for reading

[Niebel-TQ]

i.MX93 has only one pin usable for FlexSPI strobe. When using eMMC with HS400 /HS400-ES the same pin is needed as Data Strobe for eMMC. In the reference manual chapter36.8.2.2 Module Control 0 (MCR0) states, that Field RXCLKsrc=10b can be used to use higher SCLK and achieve higher read data rates.

Since this mode is not implemented in BSP: is this mode tested and usable? Looking at other i.MX CPU (i.MX8MP) the value of RXCLKsrc=10b is marked as reserved. If it can be used, are there other configurations that needs to be adjusted?

@florian_arndt +  @danny_john

[joanxie]

As I known, the customer tested this on imx8mp successfully, besides of Setting RXCLKsrc to 10b,  also setting SION to 1 on IOMUXC_SW_MUX_CTL_PAD_NAND_DQS, maybe you can try it on imx93

[Niebel-TQ]

The DQS Signal for FlexSPI is only muxable at the very same pin that is already used for EMMC Strobe. This is the reason why asking for MCR0[RXCLKSRC] = 10b (SCK output and loopback from SCK pad).

This means setting this mode _and_SION for SW_MUX_CTL_PAD_SD3_CLK muxed as FLEXSPI1_A_SCLK, rigth?

[Niebel-TQ]

We managed to modify FlexSPI driver (currently on linux 6.1) to accept different MCR0[RXCLKSRC]. First Tests with SPI 1-4-4 @114MHz looking good.

[joanxie]

glad to hear this, I will close this tread if you don't have further issue about this

[joanxie]

I confirmed that imx93 doesn't have this issue,  you can try to use this bit directly, for the clock, pls refer to the data sheet as below

[Niebel-TQ]

Just a follow up question. The mode 10b (SCLK output clock and looped back from SCLK pad) is not mentioned in the data sheet. What is the SCLK rate that is achievable in this mode?