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x86/sysfb_efi: Fix valid BAR address range check 

The code for checking whether a BAR address range is valid will break
out of the loop when a start address of 0x0 is encountered.

This behaviour is wrong since by breaking out of the loop we may miss
the BAR that describes the EFI frame buffer in a later iteration.

Because of this bug I can't use video=efifb: boot parameter to get
efifb on my new ThinkPad E550 for my old linux system hard disk with
3.10 kernel. In 3.10, efifb is the only choice due to DRM/I915 not
supporting the GPU.

This patch also add a trivial optimization to break out after we find
the frame buffer address range without testing later BARs.

Signed-off-by: Wang YanQing <udknight@gmail.com>
[ Rewrote changelog. ]
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Peter Jones <pjones@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1462454061-21561-2-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Wang YanQing 2016-05-05 14:14:21 +01:00 committed by Ingo Molnar
parent 7f9b474c92
commit c10fcb14c7
1 changed files with 12 additions and 2 deletions
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14
arch/x86/kernel/sysfb_efi.c
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@ -106,14 +106,24 @@ static int __init efifb_set_system(const struct dmi_system_id *id)
continue;
for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
resource_size_t start, end;
unsigned long flags;
flags = pci_resource_flags(dev, i);
if (!(flags & IORESOURCE_MEM))
continue;
if (flags & IORESOURCE_UNSET)
continue;
if (pci_resource_len(dev, i) == 0)
continue;
start = pci_resource_start(dev, i);
if (start == 0)
break;
end = pci_resource_end(dev, i);
if (screen_info.lfb_base >= start &&
screen_info.lfb_base < end) {
found_bar = 1;
break;
}
}
}