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Re: pending mips build fixes

To: "Ralf Baechle" <ralf@linux-mips.org>, "Atsushi Nemoto" <anemo@mba.ocn.ne.jp>
Subject: Re: pending mips build fixes
From: <danieljlaird@hotmail.com>
Date: Thu, 12 Jun 2008 20:49:06 +0100
Cc: <bunk@kernel.org>, <linux-mips@linux-mips.org>, <mb@bu3sch.de>, <aurelien@aurel32.net>, <daniel.j.laird@nxp.com>
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In-reply-to: <20080612134539.GA20487@cs181133002.pp.htv.fi> <20080612135835.GB20015@linux-mips.org> <20080613.000350.93206311.anemo@mba.ocn.ne.jp> <20080612162350.GA19234@linux-mips.org>
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Agree with the changes made

There is a larger problem however which is that I believe the 2.6.24 and later kernels broke PNX8550 support. I tried to solve the issues (see some postings some time ago) regarding timer issues and changes made between 2.6.22 (working) and 2.6.24 broken. However I could never get the fixes to work properly. I have also since moved onto pastures new with the PNX833x/893x CPUs which means solving issues for a older CPU is not top of the list. And the lifetime of 8550 willbe much shorter than the newer chipsets.

I would be tempted to mark PNX8550 / STB810 support as BROKEN. Unless other 8550 users can prove me wrong. I would not remove the code yet incase it can be rescued but would mark as BROKEN in 2.6.27 and remove in 2.6.28
Cheers
Dan

--------------------------------------------------
From: "Ralf Baechle" <ralf@linux-mips.org>
Sent: Thursday, June 12, 2008 5:23 PM
To: "Atsushi Nemoto" <anemo@mba.ocn.ne.jp>
Cc: <bunk@kernel.org>; <linux-mips@linux-mips.org>; <mb@bu3sch.de>; <aurelien@aurel32.net>; <daniel.j.laird@nxp.com>
Subject: Re: pending mips build fixes

On Fri, Jun 13, 2008 at 12:03:50AM +0900, Atsushi Nemoto wrote:

This patch fix a breakage by commit
351336929ccf222ae38ff0cb7a8dd5fd5c6236a0 > ([MIPS] Allow setting of
the cache attribute at run time.)

This patch introduce an weak __coherency_setup() to support PNX8550
which needs special handling on cache coherency updating.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

Never been a fan of weak functions though depending circumstances they
certainly can be less evil than some of the alternatives.  Also what is
hidden deep in the PNX board code really is specific to the PNX CPU core,
so I moved it to c-r4k.c.  The resulting patch is below.

 Ralf

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 643c8bc..c41ea22 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -1226,6 +1226,28 @@ void au1x00_fixup_config_od(void)
 }
}

+/* CP0 hazard avoidance. */
+#define NXP_BARRIER() \
+ __asm__ __volatile__( \
+ ".set noreorder\n\t" \
+ "nop; nop; nop; nop; nop; nop;\n\t" \
+ ".set reorder\n\t")
+
+static void nxp_pr4450_fixup_config(void)
+{
+ unsigned long config0;
+
+ config0 = read_c0_config();
+
+ /* clear all three cache coherency fields */
+ config0 &= ~(0x7 | (7 << 25) | (7 << 28));
+ config0 |= (((_page_cachable_default >> _CACHE_SHIFT) <<  0) |
+     ((_page_cachable_default >> _CACHE_SHIFT) << 25) |
+     ((_page_cachable_default >> _CACHE_SHIFT) << 28));
+ write_c0_config(config0);
+ NXP_BARRIER();
+}
+
static int __cpuinitdata cca = -1;

static int __init cca_setup(char *str)
@@ -1271,6 +1293,10 @@ static void __cpuinit coherency_setup(void)
 case CPU_AU1500: /* rev. AB */
 au1x00_fixup_config_od();
 break;
+
+ case PRID_IMP_PR4450:
+ nxp_pr4450_fixup_config();
+ break;
 }
}

diff --git a/arch/mips/nxp/pnx8550/jbs/board_setup.c b/arch/mips/nxp/pnx8550/jbs/board_setup.c
index f92826e..57dd903 100644
--- a/arch/mips/nxp/pnx8550/jbs/board_setup.c
+++ b/arch/mips/nxp/pnx8550/jbs/board_setup.c
@@ -47,16 +47,7 @@

void __init board_setup(void)
{
- unsigned long config0, configpr;
-
- config0 = read_c0_config();
-
- /* clear all three cache coherency fields */
- config0 &= ~(0x7 | (7<<25) | (7<<28));
- config0 |= (CONF_CM_DEFAULT | (CONF_CM_DEFAULT<<25) |
- (CONF_CM_DEFAULT<<28));
- write_c0_config(config0);
- BARRIER;
+ unsigned long configpr;

 configpr = read_c0_config7();
 configpr |= (1<<19); /* enable tlb */
diff --git a/arch/mips/nxp/pnx8550/stb810/board_setup.c b/arch/mips/nxp/pnx8550/stb810/board_setup.c
index 1282c27..af2a55e 100644
--- a/arch/mips/nxp/pnx8550/stb810/board_setup.c
+++ b/arch/mips/nxp/pnx8550/stb810/board_setup.c
@@ -33,15 +33,7 @@

void __init board_setup(void)
{
- unsigned long config0, configpr;
-
- config0 = read_c0_config();
-
- /* clear all three cache coherency fields */
- config0 &= ~(0x7 | (7<<25) | (7<<28));
- config0 |= (CONF_CM_DEFAULT | (CONF_CM_DEFAULT<<25) |
- (CONF_CM_DEFAULT<<28));
- write_c0_config(config0);
+ unsigned long configpr;

 configpr = read_c0_config7();
 configpr |= (1<<19); /* enable tlb */



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