On 10/18/2011 06:43 AM, Kumar Gala wrote:
quoted
quoted
Robin,
Do you remember why we went with just 'fsl,p1010-flexcan' as the device tree compatible? Do we feel the flex can on P1010 isn't the same as on MPC5xxx? or the ARM SoCs?
The decision was due to the fact there is no true "generic" fsl.flexcan
chip free of any SOC implementation and therefore not something which
could be separately defined. That decision was made by Grant Likely.
I will inline that email below.
Robin
Thanks, I'll look into this internally at FSL. I think its confusing as hell to have "fsl,p1010-flexcan" in an ARM .dts
It's confusing to have devices labelled in vague ways that we can't tie
back to any real piece of hardware, or even a public architectural spec.
If you're talking to our hardware people, ask them to put public names
and versions, guaranteed unique throughout FSL, on all of our logic
blocks -- with public block manuals that have any SW-relevant
integration parameters clearly itemized.
Why is putting "fsl,p1010-flexcan" an an ARM device any more confusing
than putting it on some PowerPC chip that is not a p1010? Think of it
like a PCI ID, the actual value not being meaningful for much other than
its uniqueness and the ability to find a manual for the hardware.
This has been the recommended practice for quite some time.
and don't think any reasonable ARM customer of FSL would know to put
a PPC SOC name in their .dts.
If an ARM device tree comes along that just has
"fsl,some-arm-chip-flexcan", so what? Let the same driver bind against
both, again like PCI IDs. Additional compatibles are mainly a
convenience to give things a chance to work before the driver is updated
(a frequent irritant with PCI IDs and new hardware).
Ideally we would be publishing a sample device tree for our ARM chips
and their peripherals, though. :-P
I'll ask the HW guys what's going on
so we can come up with a bit more generic name so we don't have to
constantly change this. Even if its just:
fsl,ppc-flexcan & fsl,arm-flexcan.
Why is CPU instruction set relevant?
Would a QorIQ customer think to check for an existing compatible in
mpc5xxx, or even mpc83xx or mpc86xx?
-Scott