[U-Boot] Why spi flash probe runs twice on Xilinx Zynq board ?

[Thomas.Betker at rohde-schwarz.com]

Hello Abdul Basit:

> .I noticed that the following lines are coming twice:
> 
> SF: Detected S25FL129P_64K/S25FL128S_64K with page size 64 KiB, total 16 
MiB
> 
> This corresponds to the function spi_flash_probe from
> drivers/mtd/spi/spi_flash.c
> 
> I need to know:
> 
> 1- Why it is probed twice?
> 2- The name and location of the file from where it is called (twice).
> 3- The second time it is being probed  is considerably slow, why it is 
so?

It is hard to tell what is happening here because so much information is 
missing, but I will venture a few guesses:

The first probe probably occurs when the environment is read, in env_sf.c; 
I am assuming that the environment is located in QSPI flash.

The second probe is probably due to a boot command which reads the Linux 
kernel from QSPI flash, and runs 'sf probe' from cmd_sf.c; try running 
'printenv'.

The flash probe itself should always take the same (rather short) amount 
of time. Reading a Linux kernel from flash is slower than reading a small 
environment block, though, because the kernel is much bigger.

Hope that helps,
Thomas Betker