From: Valentine Barshak <vbarshak@ru•mvista.com>
To: linuxppc-dev@ozlabs•org
Subject: [PATCH 3/3] PowerPC: 440EPx/GRx incorrect write to DDR SDRAM errata workaround
Date: Fri, 21 Sep 2007 18:50:09 +0400 [thread overview]
Message-ID: <20070921145009.GA4298@ru.mvista.com> (raw)
In-Reply-To: <20070921144149.GA4150@ru.mvista.com>
Add a workaround for PowerPC 440EPx/GRx incorrect write to
DDR SDRAM errata. Data can be written to wrong address
in SDRAM when write pipelining enabled on plb0. We disable
it in the cpu_setup for these processors at early init.
Signed-off-by: Valentine Barshak <vbarshak@ru•mvista.com>
---
arch/powerpc/kernel/cpu_setup_44x.S | 25 ++++++++++++++++++++++++-
arch/powerpc/kernel/cputable.c | 3 +++
2 files changed, 27 insertions(+), 1 deletion(-)
diff -ruN linux-2.6.orig/arch/powerpc/kernel/cpu_setup_44x.S linux-2.6/arch/powerpc/kernel/cpu_setup_44x.S
--- linux-2.6.orig/arch/powerpc/kernel/cpu_setup_44x.S 2007-09-21 15:31:14.000000000 +0400
+++ linux-2.6/arch/powerpc/kernel/cpu_setup_44x.S 2007-09-21 16:07:12.000000000 +0400
@@ -20,7 +20,14 @@
_GLOBAL(__setup_cpu_440ep)
b __init_fpu_44x
_GLOBAL(__setup_cpu_440epx)
- b __init_fpu_44x
+ mflr r4
+ bl __init_fpu_44x
+ bl __plb_disable_wrp
+ mtlr r4
+ blr
+_GLOBAL(__setup_cpu_440grx)
+ b __plb_disable_wrp
+
/* enable APU between CPU and FPU */
_GLOBAL(__init_fpu_44x)
@@ -31,3 +38,19 @@
isync
blr
+/*
+ * Workaround for the incorrect write to DDR SDRAM errata.
+ * The write address can be corrupted during writes to
+ * DDR SDRAM when write pipelining is enabled on PLB0.
+ * Disable write pipelining here.
+ */
+#define DCRN_PLB4A0_ACR 0x81
+
+_GLOBAL(__plb_disable_wrp)
+ mfdcr r3,DCRN_PLB4A0_ACR
+ /* clear WRP bit in PLB4A0_ACR */
+ rlwinm r3,r3,0,8,6
+ mtdcr DCRN_PLB4A0_ACR,r3
+ isync
+ blr
+
diff -ruN linux-2.6.orig/arch/powerpc/kernel/cputable.c linux-2.6/arch/powerpc/kernel/cputable.c
--- linux-2.6.orig/arch/powerpc/kernel/cputable.c 2007-09-21 15:55:23.000000000 +0400
+++ linux-2.6/arch/powerpc/kernel/cputable.c 2007-09-21 16:08:23.000000000 +0400
@@ -33,6 +33,7 @@
#ifdef CONFIG_PPC32
extern void __setup_cpu_440ep(unsigned long offset, struct cpu_spec* spec);
extern void __setup_cpu_440epx(unsigned long offset, struct cpu_spec* spec);
+extern void __setup_cpu_440grx(unsigned long offset, struct cpu_spec* spec);
extern void __setup_cpu_603(unsigned long offset, struct cpu_spec* spec);
extern void __setup_cpu_604(unsigned long offset, struct cpu_spec* spec);
extern void __setup_cpu_750(unsigned long offset, struct cpu_spec* spec);
@@ -1146,6 +1147,8 @@
.cpu_user_features = COMMON_USER_BOOKE,
.icache_bsize = 32,
.dcache_bsize = 32,
+ .cpu_setup = __setup_cpu_440grx,
+ .platform = "ppc440",
},
{ /* 440GP Rev. B */
.pvr_mask = 0xf0000fff,
next prev parent reply other threads:[~2007-09-21 14:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-21 14:41 [PATCH 0/3] PowerPC: Add cpu_setup functionality to 44x platform Valentine Barshak
2007-09-21 14:44 ` [PATCH 1/3] PowerPC: Introduce " Valentine Barshak
2007-09-21 14:46 ` [PATCH 2/3] PowerPC: Move 440EP(x) FPU setup from head_44x to cpu_setup_4xx Valentine Barshak
2007-09-21 14:50 ` Valentine Barshak [this message]
2007-09-26 21:12 ` [PATCH 0/3] PowerPC: Add cpu_setup functionality to 44x platform Josh Boyer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070921145009.GA4298@ru.mvista.com \
--to=vbarshak@ru$(echo .)mvista.com \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox