Re: Trouble with SCC UART ports when moving from ppc to powerpc

[Laurent Pinchart <laurentp@cse-semaphore.com>]

[-- Attachment #1: Type: text/plain, Size: 1979 bytes --]

On Friday 07 March 2008 17:21, Scott Wood wrote:
> On Fri, Mar 07, 2008 at 03:20:55PM +0100, Laurent Pinchart wrote:
> > The CPM dual port ram was defined in the device tree as follows (copied
> > from the MPC8272ADS board device tree).
> >
> >         muram@0 {
> >                 #address-cells = <1>;
> >                 #size-cells = <1>;
> >                 ranges = <0 0 10000>;
> >
> >                 data@0 {
> >                         compatible = "fsl,cpm-muram-data";
> >                         reg = <0 2000 9800 800>;
> >                 };
> >         };
> >
> > Changing the reg property to
> >
> > reg = <80 1f80 9800 800>;
> >
> > fixed my problem.
>
> Perhaps there's an SMC1 running with its parameter RAM at offset zero?

Good guess. U-Boot configured SMC1 with its parameter RAM at offset 0.

> > Does anyone have any clue regarding what could write to the dpram ? I
> > thought about some CPM peripheral set up by the boot loader, but my board
> > initialization code calls cpm2_reset() long before initializing SCC1.
>
> cpm2_reset() doesn't currently actually reset the CPM, for some reason
> (unlike cpm1).  This should probably be fixed, though then we'd have to
> deal with assigning SMC parameter RAM addresses ourselves.

I had overlooked that. Resetting the CPM in cpm2_reset() helps. Is there any 
reason not to rset the CPM in cpm2_reset() ?

How should SMC parameter RAM assignment be handled ? I'm not very familiar 
with the CPM1, but for CPM2 the cpm_uart driver could easily cpm_dpalloc() 
parameter RAM.

> For now, the above fix should be done on any board with an active SMC
> device (assuming SMC parameter RAM at zero, as u-boot sets it; other
> bootloaders may need to exempt a different region).

Thanks for your help.

Best regards,

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussée de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]