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

From: Wolfram Sang <[email-masked]>
Date: Mon, 18 Aug 2008 16:18:31 +0200

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 <[email-masked]>
---
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