Verdin iMX8M-Plus datasheet (verdin_imx8m_plus_datasheet.pdf) mentions the max speed of ECSPI ports by indicating that
The SPI ports operate at up to 60 Mbps in master write mode and up to 30 Mbps in master read
mode.
But it didn’t say anything about FlexSPI used by Quad SPI. Is it same as ECSPI?
I also wonder that why read and write speeds differ. When a data outs on the SPI MOSI port, MISO should be sampled at the same time or at the following negative clk edge. This is not the case here?
Did you check IMX8M-Plus datasheets at NXP?
As I see top QSPI SDR mode clock is 133MHz, DDR - 66MHz.
Regarding lower master read frequency, SPI is not always about memories. Sometimes the only requirement is to stream out data without any reading. I see nothing wrong if they guarantee faster write-only speed, though really unusual.
Yes I have checked both Reference Manual and Device Datasheet but they were not clear to me.
In the datasheet QSPI_CLK_ROOT is reported as 400MHz and ECSPI1_CLK_ROOT as 80MHz.
I still don’t know how Toradex came up with these values 60Mbps write and 30Mbps read speed.
