Re: HPET regression in 2.6.26 versus 2.6.25 -- found another user with the same regression

["Yinghai Lu" <yhlu.kernel@gmail.com>]

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On Sun, Aug 24, 2008 at 6:05 AM, David Witbrodt <dawitbro@sbcglobal.net> wrote:
>
>
>> > - Is there any chance I can get it into the stable 2.6.26.X updates?
>> > (Who should I ask, or are only developers allowed to lobby for this
>> > sort of thing?)
>>
>> after the patch get into linus tree. Greg will put the patch into 2.6.26.X
>
> OK, thanks a bunch.
>
>
>> > - Are you worried about the potential problems of a quirk-based approach?
>> > What if many more people experience a similar regression once 2.6.26 or
>> > later appears in their distribution?  I'm sure you don't want to have to
>> > write a different quirk for each individual's hardware, and this problem
>> > did not arise with the approach used for resource management in 2.6.25.
>>
>> this patch should be safe.
>>
>> 2.6.26 is fixing one bug about reserving local apic address and that
>> in e820 table.
>> and it reveals one bios bug.
>
> Correction -- it revealed at least two.  See the link I posted earlier in
> this thread:
>
> http://www.uwsg.indiana.edu/hypermail/linux/kernel/0808.2/1807.html
>
> Scroll down to the line that starts with "[blog]" for the link. You can see
> the discussion I had encouraging him to come here to help us troubleshoot
> if you go to that blog and click "Comments".
>
> I only mention this as a warning, in case it could lead to a lot of extra
> problems for you later.  If you're quite sure that everything is OK, then
> all I can do is thank you again and keep my fingers crossed for you and the
> kernel team that nothing bad happens when 2.6.2[67] hit the major distros.

after discussing with Ingo, we have one more generic way to detect the
same situation.

please help to verify the attached patch. ( don't apply previous patch)

YH

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[PATCH] x86: check hpet with BAR

insert some resources to resource tree forcily, so could avoid kernel update the
resources in pci device.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

---
 arch/x86/pci/i386.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

Index: linux-2.6/arch/x86/pci/i386.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/i386.c
+++ linux-2.6/arch/x86/pci/i386.c
@@ -33,6 +33,7 @@
 #include <linux/bootmem.h>
 
 #include <asm/pat.h>
+#include <asm/hpet.h>
 
 #include "pci.h"
 
@@ -77,6 +78,30 @@ pcibios_align_resource(void *data, struc
 }
 EXPORT_SYMBOL(pcibios_align_resource);
 
+static int check_res_with_valid(struct pci_dev *dev, struct resource *res)
+{
+	unsigned long base;
+	unsigned long size;
+
+	base = res->start;
+	size = (res->start == 0 && res->end == res->start) ? 0 :
+		 (res->end - res->start + 1);
+
+	if (!base || !size)
+		return 0;
+
+#ifdef CONFIG_HPET_TIMER
+	/* for hpet */
+	if (base == hpet_address && (res->flags & IORESOURCE_MEM)) {
+		dev_info(&dev->dev, "BAR has HPET at %08lx-%08lx\n",
+				 base, base + size - 1);
+		return 1;
+	}
+#endif
+
+	return 0;
+}
+
 /*
  *  Handle resources of PCI devices.  If the world were perfect, we could
  *  just allocate all the resource regions and do nothing more.  It isn't.
@@ -128,6 +153,24 @@ static void __init pcibios_allocate_bus_
 				pr = pci_find_parent_resource(dev, r);
 				if (!r->start || !pr ||
 				    request_resource(pr, r) < 0) {
+					if (check_res_with_valid(dev, r)) {
+						struct resource *root = NULL;
+
+						/*
+						 * forcibly insert it into the
+						 * resource tree
+						 */
+						if (r->flags & IORESOURCE_MEM)
+							root = &iomem_resource;
+						else if (r->flags & IORESOURCE_IO)
+							root = &ioport_resource;
+
+						if (root) {
+							insert_resource(root, r);
+						}
+						continue;
+					}
+
 					dev_err(&dev->dev, "BAR %d: can't "
 						"allocate resource\n", idx);
 					/*