[PATCH V2] MPC52XX: Don't touch pipelining for MPC5200B

[roger blofeld]

----- Original Message ----

> From: Wolfram Sang <w.sang at pengutronix.de>
> To: Arnd Bergmann <arnd at arndb.de>
> Cc: linuxppc-embedded at ozlabs.org
> Sent: Monday, August 18, 2008 9:18:31 AM
> Subject: [PATCH V2] MPC52XX: Don't touch pipelining for MPC5200B
> 
> 
> MPC5200 needs to have pipelining disabled for ATA to work. MPC5200B does not.
> So, for the latter, don't touch the original setting from the bootloader.
> 
> Signed-off-by: Wolfram Sang 
> ---
> Hello Arnd,
> 
> On Mon, Aug 18, 2008 at 12:49:36PM +0200, Arnd Bergmann wrote:
> 
> > Please make this a run-time conditional instead of compile-time.
> Like this?
> 
> ..................................................................
> 
> This needs some testing IMHO. Most configs in U-Boot tend to enable pipelining,
> which then used to be disabled by the kernel. So, on the one hand, this change
> would enable what is originally wanted; on the other hand, systems may run
> under a new configuration and need to be checked for regressions. Especially as
> there can be puzzling effects, like for one setup here, FEC only works reliably
> with pipelining enabled.
> 
> arch/powerpc/platforms/52xx/mpc52xx_common.c |    7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Index: arch/powerpc/platforms/52xx/mpc52xx_common.c
> ===================================================================
> --- arch/powerpc/platforms/52xx/mpc52xx_common.c.orig
> +++ arch/powerpc/platforms/52xx/mpc52xx_common.c
> @@ -99,11 +99,14 @@
>     out_be32(&xlb->master_pri_enable, 0xff);
>     out_be32(&xlb->master_priority, 0x11111111);
> 
> -    /* Disable XLB pipelining
> +    /*
> +     * Disable XLB pipelining
>      * (cfr errate 292. We could do this only just before ATA PIO
>      *  transaction and re-enable it afterwards ...)
> +     * Not needed on MPC5200B.
>      */
> -    out_be32(&xlb->config, in_be32(&xlb->config) | MPC52xx_XLB_CFG_PLDIS);
> +    if ((mfspr(SPRN_SVR) & MPC5200_SVR_MASK) == MPC5200_SVR)
> +        out_be32(&xlb->config, in_be32(&xlb->config) | MPC52xx_XLB_CFG_PLDIS);
> 
>     iounmap(xlb);
> }
> 
> -- 
>   Dipl.-Ing. Wolfram Sang | http://www.pengutronix.de
> Pengutronix - Linux Solutions for Science and Industry


Hi
 Since this bug is ATA specific, shouldn't this code be conditioned by CONFIG_IDE ?

Thanks
-roger