Re: [PATCH] spi/spi-altera: Allow to explicitely override bus number via dts

quoted

I wrote a piece of code that uses this nvSRAM as a persistent storage.
This runs in a softcore embedded in an FPGA, in an equipment.
The PC version of this application uses a simple file to emulate this
behavior.
The simulated version, using an x86 port embedded in a VirtualBox uses a
piece of virtual disk with /dev/sdb.

So it's just a basic block device?

It is the purpose of AT25, yes.

 > To sumarize, I have a same code that works for the 3 architecture, the

quoted

single difference being in the device name:
/sys/proc/spi/drivers/at25/spi0.0/eeprom for Nios2
dataBase.dat on Linux
/dev/sdb on the Virtual Machine

In this case surely the mechanisms used to identify regular disks (UUIDs
and so on) will also work (the .dat file will have to be an override,
but otherwise...)?  Names like sdb aren't stable either - they can
change with either software or hardware changes since they just come
from the order of discovery.

Sure there are mechanisms, but that means that the code must be either
specific to the arch, either have the code for all of them. Not simple !

The other issue with your patch is that setting a bus number is

obviously not a device specific thing, it's something that will apply to
any SPI controller on Linux, and so shouldn't be something driver
specific but should instead be a change to the SPI core.

Although I tend to agree you on the fact that SPI bus num is a SPI core
matter, but the fact is that, for now, it is the controller that must fill
the spi_master structure to call spi_master_get(), and that this structure
contains a field 'bus_num' that is always initialized to -1 since DTS...

-- 
Fred
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