[Nouveau] Resource map sanity check fails after GRUB "keeps" the gfx mode

[Pavel Roskin]

Hello!

I have spent some time on the issue.  I'm not sure it's a nouveau bug.
I have a fix that changes arch/x86/kernel/sysfb_simplefb.c only.

GRUB actually uses graphic mode on my card.  That mode is supported by
simplefb.  However, the resource conflict happens regardless of whether
simplefb is enabled.  It's sysfb_simplefb that causes it, a completely
different driver.

If GRUB keeps the graphic mode, I have this entry in /proc/iomem:

      f1000000-f112bfff : BOOTFB

It is reserved by sysfb_simplefb.  Nouveau tries to map an area at
0xf0000000-0xf1ffffff, so it includes the existing resource without
being equivalent to it.

Nouveau correctly calls remove_conflicting_framebuffers() before trying
to map that resource.  However, sysfb_simplefb is not a real
framebuffer, so it doesn't free its resources.

iomem_map_sanity_check() doesn't check regions with IORESOURCE_BUSY
set.  That's the comment from the code:

    /*
     * if a resource is "BUSY", it's not a hardware resource
     * but a driver mapping of such a resource; we don't want
     * to warn for those; some drivers legitimately map only
     * partial hardware resources. (example: vesafb)
     */

So I added IORESOURCE_BUSY to sysfb_simplefb.c and the problem is fixed
now.  Actually, it prevents nvidiafb from claiming the device:

nvidiafb 0000:01:00.0: BAR 3: can't reserve [mem 0xf0000000-0xf1ffffff
64bit pref]

But maybe that's the point of sysfb_simplefb?  Anyway, here's the
patch/hack, signed off in case it's correct :)



sysfb_simplefb: mark BOOTFB resource as busy

From: Pavel Roskin <proski at gnu.org>

This fixes a warning when nouveau tries to allocate a larger iomem area:

resource map sanity check conflict: 0xf0000000 0xf1ffffff 0xf1000000
0xf112bfff BOOTFB

iomem_map_sanity_check() specifically excludes busy regions from
checking.
---
 arch/x86/kernel/sysfb_simplefb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c
index 22513e9..b7bb615 100644
--- a/arch/x86/kernel/sysfb_simplefb.c
+++ b/arch/x86/kernel/sysfb_simplefb.c
@@ -79,7 +79,7 @@ __init int create_simplefb(const struct screen_info *si,
 
 	/* setup IORESOURCE_MEM as framebuffer memory */
 	memset(&res, 0, sizeof(res));
-	res.flags = IORESOURCE_MEM;
+	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 	res.name = simplefb_resname;
 	res.start = si->lfb_base;
 	res.end = si->lfb_base + len - 1;


-- 
Regards,
Pavel Roskin