The unaligned ioread32() will make us read byte by byte looking for the
vbt. We could just as well have done a ioread8() + a shift and avoid the
extra confusion on how we are looking for "$VBT".
However when using ACPI it's guaranteed the VBT is 4-byte aligned
per spec, so we can probably assume it here as well.
Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_bios.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 3ab73f8db8dd..328bc6b6157f 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -1802,27 +1802,20 @@ static struct vbt_header *oprom_get_vbt(struct drm_i915_private *dev_priv)
void __iomem *p = NULL, __iomem *oprom;
struct vbt_header *vbt;
u16 vbt_size;
- size_t i, size;
+ size_t size;
oprom = pci_map_rom(pdev, &size);
if (!oprom)
return NULL;
/* Scour memory looking for the VBT signature. */
- for (i = 0; i + 4 < size; i++) {
- if (ioread32(oprom + i) != *((const u32 *)"$VBT"))
- continue;
-
- p = oprom + i;
- size -= i;
- break;
- }
-
- if (!p)
- goto err_unmap_oprom;
+ for (p = oprom; size >= 4; p += 4, size -= 4)
+ if (ioread32(p) == *((const u32 *)"$VBT"))
+ break;
if (sizeof(struct vbt_header) > size) {
- DRM_DEBUG_DRIVER("VBT header incomplete\n");
+ if (size >= 4)
+ DRM_DEBUG_DRIVER("VBT header incomplete\n");
goto err_unmap_oprom;
}
--
2.24.0
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