x86:sysfb_efi:efifb_set_system: fix miss valid address range in later BARs

We can't just break out when meet start is equal to zero, this will cause we miss valid address range in later BARs.

On the other hand, it isn't enough to test start only for below situation:
0(start) <= lfb_base < end

Note: this patch also add a trivial optimization,
break out after we find the address range
is valid without test later BARs.

Signed-off-by Wang YanQing <[email protected]>

---
Due to the BUG this patch fix, 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 in it doesn't support the GPU.

Changes:
v1-v2:
1: Do a trivial code optimization.

 arch/x86/kernel/sysfb_efi.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

arch/x86/kernel/sysfb_efi.c +12 -2

index b285d4e..5da924b 100644
@@ -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;
 					}
 				}
 			}

Signature · 1 line

1.8.5.6.2.g3d8a54e.dirty

Quoted 11 lines · Wang YanQing

We can't just break out when meet start is equal to zero, this will cause we miss valid address range in later BARs.

On the other hand, it isn't enough to test start only for below situation:
0(start) <= lfb_base < end

Note: this patch also add a trivial optimization,
break out after we find the address range
is valid without test later BARs.

Quoted 1 line

Signed-off-by Wang YanQing <[email protected]>

This looks correct to me:

Reviewed-by Peter Jones <[email protected]>

Cc'ing Matt Fleming, since this should probably go through the EFI tree.