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Re: [MIPS] SMTC: Fix crash on bootup with idebus= command line argument.

To: ralf@linux-mips.org
Subject: Re: [MIPS] SMTC: Fix crash on bootup with idebus= command line argument.
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Tue, 04 Sep 2007 23:02:02 +0900 (JST)
Cc: chris@mips.com, linux-mips@linux-mips.org
In-reply-to: <20070904125010.GA15630@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070904.000501.41013092.anemo@mba.ocn.ne.jp> <46DC2D2E.8080408@mips.com> <20070904125010.GA15630@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
On Tue, 4 Sep 2007 13:50:10 +0100, Ralf Baechle <ralf@linux-mips.org> wrote:
> > The bug wasn't really SMTC specific, it was just that it showed up on 
> > SMTC builds. The failure was caused by the early parsing of the 
> > idebus=xx argument. The argument parser ended up calling
> > pci_scan that unconditionally enabled interrupts prematurely.
> 
> Which at the time did also happen for x86 - it just happened to be a
> harmless bug there.

Hmm, I see.  Then I think no_pci_device() can be used to avoid such
case, as like as pci_find_subsys().

Anyway the commit 00cc123703425aa362b0af75616134cbad4e0689 may change
ide numbering for swarm or au1xxx (if those platform did not have ISA
brigdes).  How about this?


Subject: No ide_default_io_base() if PCI IDE was not found

Revert b5438582090406e2ccb4169d9b2df7c9939ae42b and add
no_pci_devices() check to avoid crash due to early calling of
pci_get_class().

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
---
diff --git a/include/asm-mips/mach-generic/ide.h 
b/include/asm-mips/mach-generic/ide.h
index 2b92857..a771283 100644
--- a/include/asm-mips/mach-generic/ide.h
+++ b/include/asm-mips/mach-generic/ide.h
@@ -29,6 +29,35 @@
 
 #define IDE_ARCH_OBSOLETE_DEFAULTS
 
+static __inline__ int ide_probe_legacy(void)
+{
+#ifdef CONFIG_PCI
+       struct pci_dev *dev;
+       /*
+        * This can be called on the ide_setup() path, super-early in
+        * boot.  But the down_read() will enable local interrupts,
+        * which can cause some machines to crash.  So here we detect
+        * and flag that situation and bail out early.
+        */
+       if (no_pci_devices())
+               return 0;
+       dev = pci_get_class(PCI_CLASS_BRIDGE_EISA << 8, NULL);
+       if (dev)
+               goto found;
+       dev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
+       if (dev)
+               goto found;
+       return 0;
+found:
+       pci_dev_put(dev);
+       return 1;
+#elif defined(CONFIG_EISA) || defined(CONFIG_ISA)
+       return 1;
+#else
+       return 0;
+#endif
+}
+
 static __inline__ int ide_default_irq(unsigned long base)
 {
        switch (base) {
@@ -45,6 +74,8 @@ static __inline__ int ide_default_irq(unsigned long base)
 
 static __inline__ unsigned long ide_default_io_base(int index)
 {
+       if (!ide_probe_legacy())
+               return 0;
        /*
         *      If PCI is present then it is not safe to poke around
         *      the other legacy IDE ports. Only 0x1f0 and 0x170 are

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