V4L/DVB (5023): Fix compilation on ppc32 architecture

There's a problem, pointed by Meelis Roos <mroos@linux.ee>, that, on ppc32 arch,
with some gcc versions (noticed with prerelease 4.1.2 20061115), compilation 
fails, due the lack of __ucmpdi2 to do the required 64-bit comparision.
This patch takes some sugestions made by Andrew Morton <akpm@osdl.org>,
Stelian Pop <stelian@popies.net> and Segher Boessenkool <segher@kernel.crashing.org>

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

2 files changed, 17 insertions, 1 deletions

diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index 752c82c37f55..b87d571e0463 100644
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -90,8 +90,15 @@ MODULE_LICENSE("GPL");
 char *v4l2_norm_to_name(v4l2_std_id id)
 {
         char *name;
+        u32 myid = id;
 
-        switch (id) {
+        /* HACK: ppc32 architecture doesn't have __ucmpdi2 function to handle
+           64 bit comparations. So, on that architecture, with some gcc variants,
+           compilation fails. Currently, the max value is 30bit wide.
+         */
+        BUG_ON(myid != id);
+
+        switch (myid) {
         case V4L2_STD_PAL:
                 name="PAL";             break;
         case V4L2_STD_PAL_BG:
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 5cb380a559fd..d94e2683be52 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -662,6 +662,15 @@ typedef __u64 v4l2_std_id;
 #define V4L2_STD_ATSC_8_VSB     ((v4l2_std_id)0x01000000)
 #define V4L2_STD_ATSC_16_VSB    ((v4l2_std_id)0x02000000)
 
+/* FIXME:
+   Although std_id is 64 bits, there is an issue on PPC32 architecture that
+   makes switch(__u64) to break. So, there's a hack on v4l2-common.c rounding
+   this value to 32 bits.
+   As, currently, the max value is for V4L2_STD_ATSC_16_VSB (30 bits wide),
+   it should work fine. However, if needed to add more than two standards,
+   v4l2-common.c should be fixed.
+ */
+
 /* some merged standards */
 #define V4L2_STD_MN     (V4L2_STD_PAL_M|V4L2_STD_PAL_N|V4L2_STD_PAL_Nc|V4L2_STD_NTSC)
 #define V4L2_STD_B      (V4L2_STD_PAL_B|V4L2_STD_PAL_B1|V4L2_STD_SECAM_B)