[U-Boot] A problem about 'sf probe' using DM_SPI

[Qianyu Gong]

Hi Simon,

I think I'm not very clear with this code in common/cmd_sf.c:
"
# ifdef CONFIG_DM_SPI_FLASH
       /* Remove the old device, otherwise probe will just be a nop */
       ret = spi_find_bus_and_cs(bus, cs, &bus_dev, &new);
       if (!ret) {
              device_remove(new);
             device_unbind(new);
     }
"
I may understand the remove but why need to unbind the device?
The unbind would cause a series of free operations on the device list, correct?

Then if I probe a flash twice, at the second time the driver model will create
a new flash named 'spi_flash at xx:xx' using default settings because it doesn't
find such a device in the device list and never probes it from the board's fdt again.

=> dm tree
Class       Probed   Name
----------------------------------------
root        [ + ]    root_driver
simple_bus  [ + ]    `-- soc
spi         [ + ]           |-- dspi at 2100000
spi_flash   [   ]        |    |-- n25q128a
spi_flash   [ + ]        |   |-- spi_flash at 1:1
spi_flash   [ + ]        |   `-- spi_flash at 1:2

Fortunately the default SPI mode set by U-Boot is SPI_MODE_3 so it doesn't cause
issues on our boards. But if an SPI flash which only supports SPI_MODE_0 is used,
I think it wouldn't work properly from the second probe.


Sorry if there is something wrong with my understandings.
Just because I found my flash's name was changed to spi-flash at xx:xx in dm tree
after several probes, I began to read something about driver model.:)


Regards,
Qianyu