drm/nouveau/bios: fix DCB v1.5 parsing

memcmp->nv_strncmp conversion, in addition to name change, should have
inverted the return value.

But nv_strncmp does not act like strncmp - it does not check for string
terminator, returns true/false instead of -1/0/1 and has different
parameters order.

Let's rename it to nv_memcmp and let it act like memcmp.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 10 insertions, 6 deletions

diff --git a/drivers/gpu/drm/nouveau/core/include/core/object.h b/drivers/gpu/drm/nouveau/core/include/core/object.h
index 818feabbf4a0..486f1a9217fd 100644
--- a/drivers/gpu/drm/nouveau/core/include/core/object.h
+++ b/drivers/gpu/drm/nouveau/core/include/core/object.h
@@ -175,14 +175,18 @@ nv_mo32(void *obj, u32 addr, u32 mask, u32 data)
         return temp;
 }
 
-static inline bool
-nv_strncmp(void *obj, u32 addr, u32 len, const char *str)
+static inline int
+nv_memcmp(void *obj, u32 addr, const char *str, u32 len)
 {
+        unsigned char c1, c2;
+
         while (len--) {
-                if (nv_ro08(obj, addr++) != *(str++))
-                        return false;
+                c1 = nv_ro08(obj, addr++);
+                c2 = *(str++);
+                if (c1 != c2)
+                        return c1 - c2;
         }
-        return true;
+        return 0;
 }
 
 #endif
diff --git a/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c b/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
index 7d750382a833..c51197157749 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
@@ -64,7 +64,7 @@ dcb_table(struct nouveau_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len)
                 }
         } else
         if (*ver >= 0x15) {
-                if (!nv_strncmp(bios, dcb - 7, 7, "DEV_REC")) {
+                if (!nv_memcmp(bios, dcb - 7, "DEV_REC", 7)) {
                         u16 i2c = nv_ro16(bios, dcb + 2);
                         *hdr = 4;
                         *cnt = (i2c - dcb) / 10;