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Re: [PATCH v2] MIPS: cavium-octeon: fix I/O space setup on non-PCI syste

To: Aaro Koskinen <aaro.koskinen@iki.fi>
Subject: Re: [PATCH v2] MIPS: cavium-octeon: fix I/O space setup on non-PCI systems
From: David Daney <ddaney@caviumnetworks.com>
Date: Mon, 22 Jul 2013 13:58:05 -0700
Cc: David Daney <ddaney.cavm@gmail.com>, Ralf Baechle <ralf@linux-mips.org>, David Daney <david.daney@cavium.com>, Faidon Liambotis <paravoid@debian.org>, <linux-mips@linux-mips.org>
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On 07/22/2013 01:39 PM, Aaro Koskinen wrote:
On Mon, Jul 22, 2013 at 01:08:51PM -0700, David Daney wrote:
On 07/22/2013 12:55 PM, Aaro Koskinen wrote:
Fix I/O space setup, so that on non-PCI systems using inb()/outb()
won't crash the system. Some drivers may try to probe I/O space and for
that purpose we can just allocate some normal memory initially. Drivers
trying to reserve a region will fail early as we set the size to 0. If
a real I/O space is present, the PCI/PCIe support code will re-adjust
the values accordingly.

Tested with EdgeRouter Lite by enabling CONFIG_SERIO_I8042 that caused
the originally reported crash.

Reported-by: Faidon Liambotis <paravoid@debian.org>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
---

        v2: Address the issues found from the first version of the patch
            (http://marc.info/?t=137434204000002&r=1&w=2).

  arch/mips/cavium-octeon/setup.c | 28 ++++++++++++++++++++++++++++
  arch/mips/pci/pci-octeon.c      |  9 +++++----
  2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index 48b08eb..6775bd1 100644
--- a/arch/mips/cavium-octeon/setup.c
+++ b/arch/mips/cavium-octeon/setup.c
@@ -8,6 +8,7 @@
   *   written by Ralf Baechle <ralf@linux-mips.org>
   */
  #include <linux/compiler.h>
+#include <linux/vmalloc.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/console.h>
@@ -1139,3 +1140,30 @@ static int __init edac_devinit(void)
        return err;
  }
  device_initcall(edac_devinit);
+
+static void __initdata *octeon_dummy_iospace;
+
+static int __init octeon_no_pci_init(void)
+{
+       /*
+        * Initially assume there is no PCI. The PCI/PCIe platform code will
+        * later re-initialize these to correct values if they are present.
+        */
+       octeon_dummy_iospace = vzalloc(IO_SPACE_LIMIT);
+       set_io_port_base((unsigned long)octeon_dummy_iospace);
+       ioport_resource.start = MAX_RESOURCE;
+       ioport_resource.end = 0;
+       return 0;
+}
+arch_initcall(octeon_no_pci_init);
+

Do we have any guarantee that this will happen before the
arch/mips/pci/* arch_initcalls ?

Yes, it's guaranteed by the linking order ie. in which order the obj-y
stuff gets listed in mips/Makefile. Currently cavium-octeon/ is processed
before pci/.


Yes, I understand that. The problem is when we start to use things like GCC's LTO, where we effectively compile the entire kernel as a single file. Will this still work then? I would rather not screw around with it.

Can you test it by making it a core_initcall() instead? If that works you can add Acked-by: me.

Thanks,
David Daney


Quoting including/linux/init.h:

/* initcalls are now grouped by functionality into separate
  * subsections. Ordering inside the subsections is determined
  * by link order.

A.



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