From 0fb61eeb7efdc91cfb2006e926103ffb9aa79574 Mon Sep 17 00:00:00 2001
From: Lucas De Marchi <lucas.demarchi@intel.com>
Date: Tue, 26 Nov 2019 14:51:10 -0800
Subject: drm/i915/bios: assume vbt is 4-byte aligned into oprom
Git-commit: 98cf5c9a482d975b91d2cf00e09c061b535b8ee4
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
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 "$VBT".
However when using ACPI it's guaranteed the VBT is 4-byte aligned
per spec, so we can probably assume it here as well.
v2: do not try to simplify the loop by eliminating the auxiliary counter
(Jani and Ville)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191126225110.8127-4-lucas.demarchi@intel.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/display/intel_bios.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index b75db4a2e42f..1aeecdd02293 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -1938,7 +1938,7 @@ static struct vbt_header *oprom_get_vbt(struct drm_i915_private *dev_priv)
return NULL;
/* Scour memory looking for the VBT signature. */
- for (i = 0; i + 4 < size; i++) {
+ for (i = 0; i + 4 < size; i += 4) {
if (ioread32(oprom + i) != *((const u32 *)"$VBT"))
continue;
--
2.28.0