Grant Likely wrote:

On Thu, Mar 26, 2009 at 9:33 AM, Wolfgang Grandegger [off-list ref] wrote:

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Grant Likely wrote:

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Does using the reg property give the driver enough information to
reliably program the MAR for NAND connections that use the address
line chip select scheme?  Related to that, should the binding include

In principle yes:

 if (i > 0)
     offset[i] = resource[i].start - resource[0].start;

Ewww.  That's ugly.

Yep.

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a property that explicitly states that an address line chip select
scheme is being used?

That's why I'm still in favor of:

 fsl,upm-multi-chip-offsets = <0x200 0x400>

That would state that the address line chip select scheme is used with
the specified offsets. It also allows for a more elegant solution
(code-wise).

Alright.  Then at the very least the property name should reflect that
address lines CS is used to reduce the chance of confusion with
another multi-chip scheme.  Something like
fsl,upm-addr-line-cs-offsets maybe?

Here is another thought.  The binding is describing that address lines
are used to activate CS lines.  Offset for chip access purposes is
derived from the address line, but it doesn't directly describe the
hardware.  The following may be a better description of the hardware.

fsl,upm-addr-line-cs = <9 10>;

The TQM8548 hardware has some logic connected to the two address lines
allowing to select up to 4 chips with two address lines:

 fsl,upm-addr-line-cs-offsets = <0x0 0x200 0x400 0x600>

That's the more general solution.

Wolfgang.