[U-Boot-Users] uboot clock configuration on mpc5200 boards

[Grant Likely]

On 11/20/07, Jon Smirl <jonsmirl at gmail.com> wrote:
> On the Linux kernel the mpc52xx_setup_cpu() function used to do this
> fix up. Does uboot handle this for mpc5200 boards? If so, which
> version?
>
> uboot is accessing these registers but it is not clear to me if the
> clocks are completely being set up.
>
> The 5200lite code has been changed to this:
>
> /*
>  * Fix clock configuration.
>  *
>  * Firmware is supposed to be responsible for this.  If you are creating a
>  * new board port, do *NOT* duplicate this code.  Fix your boot firmware
>  * to set it correctly in the first place
>  */
> static void __init
> lite5200_fix_clock_config(void)
> {
----8<----snip---->8----
> }
>
> Is uboot setting this up correct now that they kernel has been changed?
>

Strictly speaking; firmware should be responsible for configuring the
SoC (clocks, pinouts, etc).  It makes it easier to add new boards if
each one doesn't need it's own fixups.

I haven't checked the clock setup for lite5200 in u-boot yet, but it
is not a complex change.  And even if I do change it for the lite5200
in u-boot; this code probably won't go away in the kernel so as not to
break compatibility with lite5200's with older u-boot firmware.

The point is that firmware should setup the CPU correctly at boot.  It
should not be Linux's responsibility.  However, if there is *existing*
firmware that needs to be supported; then I'll grudgingly accept hacks
like this to keep the board bootable.  If it is a new board, do it
right the first time and do it in firmware (be it u-boot or otherwise)

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely at secretlab.ca
(403) 399-0195