Re: [RFC][PATCH] SPI subsystem

[Vital <vitalhome@rbcmail.ru>]

Mark Underwood wrote:

> > Same as for suspend.
> >
> > And the basic idea anyway looks wrong and not
> > LDM'ish.
> > What if your driver
> >
> > +static struct device_driver spi_adapter_driver = {
> > + .name = "spi_adapter",
> > + .bus = &spi_bus_type,
> > + .probe = spi_adapter_probe,
> > + .remove = spi_adapter_remove,
> > +};
> >
> > presents also suspend/resume functions (what it
> > should have done anyway).
> >
> > Won't it be in a clash with your suspend/resume
> > technique?
> >    
>
> Probably as I said above I don't know enough about
> this area yet. Maybe you could help me to do this
> correctly?
>
>  
I guess that it's basically wrong to use platform_device here. My POV is 
that a specific spi_device structure should be introduced here, just 
like pcidevice, for instance.

> > Also:
> >
> > Can you please specify what is the difference
> > between 'bus' and 'chip' 
> > in your model?
> >    
>
> My current terminology is:
>
> spi adapter: A device that sits on an bus (platform,
> PCI, USB etc) and is a SPI master and/or slave (I
> haven't done any work on the slave part yet).
>
> spi device: A SPI device (e.g. a SPI eeprom) which one
> or more of are connected to a spi adapter.
>
>  
>
> > It's not clear to me how the following situation is
> > handled. Suppose you 
> > have two SPI 'busses' with same devices (for
> > instance, 2 SD card 
> > adapters) attached to different busses.
> >    
>
> I don't understand your question here. You would have
> two instances of a SD card adapter. In sysfs it would
> look like:
>
> SD card 0
> /sys/devices/platform/spi-0/0-0000
>
> SD card 1
> /sys/devices/platform/spi-1/1-0002
>
> As far as the SD card driver is concernedit doesn't
> need to know which one its driving or even how many of
> them they are. The big advantage of using the LDM.
>  
Not sure if I get you right.
If we suspend bus 0, how does the SD driver get aware of that?

Vitaly
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