On Wed, Feb 18, 2009 at 03:02:00PM -0800, David Brownell wrote: > On Wednesday 18 February 2009, Mark A. Greer wrote: > > The Davinci cpu_is_davinci_*() macros use the platform part number > > and variant retrieved from the JTAG ID register to ultimately determine > > the cpu type that the kernel is running on. Unfortunately, some newer > > Davinci-like platforms have the JTAG ID register at a different address > > than where the true Davincis have it. So, in order to know the address > > of the JTAG ID register, we have to know the cpu type...but that's why > > we're reading the JTAG ID register in the first place (i.e., chicken & egg). > > > > Instead, use the SoC info infrastructure that's already there to set > > the cpu id and reference that id with the 'is_davinci_*()' macro. > > Are you sure it's a good idea to remove the hooks for looking > at the chip ID registers though? > > DaVinci may not need to cope with chiprev-specific issues yet, > and support for product variants is a bit weak for now, but > I'd be tempted to leave the "id.c" file around and just use > that (new) infrastructure to say how to get at ID registers.
Good point. I should probably change the board file *_map_io() routines back to calling dm355_init(), etc. which would figure out the rev or do any other SoC specific init. The *_init() routines would then call davinci_soc_init(). I think this is still a gain over resurrecting id.c but that's MHO. > These changes expect boards only to ever use one chiprev and > product variant, which seems like a dubious model to impose > on the board manufacturing side ... which may need to shift > to lower cost or bugfixed versions over time, ideally without > coupling such changes to new software releases. Agreed but the support isn't there in the old code, not required yet, and can be handled pretty easily with the changes mentioned above so I'd still like to get rid of id.c. How fiercely do you object to that? Mark -- _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
