On Thu, 23 Dec 2010 15:33:25 -0700 Grant Likely <grant.lik...@secretlab.ca> wrote:
> On Thu, Dec 23, 2010 at 03:49:54PM -0600, Meador Inge wrote: > > How do you > > see this working in terms of processing the data? It seems like we > > are going to have to be aware of N values instead of 1, which seems > > worse. > > This argument has been rehashed many times, but it basically comes > down to compatible values should ideally be anchored to a real > implemented device, not to a family of devices, or to an unversioned > specification. Freescale MPICs do have version numbers (version registers, even). We should put that version (possibly along with a compatible version) in the compatible, though, for blocks such as this which don't include the main MPIC registers and thus the version registers. > In practise, the implementation doesn't actually look any different > except that the 'reference' version specifies a specific > implementation instead of a generic name. To use a concrete example, > if there are two parts using this MPIC, like the freescale p2040 and > p4080, and say for argument that the p2040 was implemented first, then > the compatible values would look like: > > for the p2040: compatible = "fsl,p2040-msgr"; > for the p4080: compatible = "fsl,p4080-msgr", "fsl,p2040-msgr"; While I don't think it affected the message unit, p4080 rev 1 has a different version of the MPIC from p4080 rev 2 (4.0 versus 4.1, IIRC). I don't think "mpic-" should be dropped, whether a specific chip is added or not. "msgr" just seems too generic, and "mpic-" tells the reader where in the chip manual they can find information about it. > > >? This needs some more explanation. cell-index often gets abused as > > >a way to enumerate devices. Typically, the address of the device > > >itself is sufficient to identify the device. > > > > The message registers typically come in blocks of four memory mapped > > registers and may not be in contiguous memory (example [3]). The > > intent of 'cell-index' is to put an ordering on the blocks (so, yes, > > enumeration). We could order them by address as well I suppose. > > One less property to worry about :) But why do we care about ordering them? What's important is just that you use the same one on both the sending partition and the receiving partition. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev