[PATCH 4.4 075/241] fbdev: sm712fb: fix memory frequency by avoiding a switch/case fallthrough

From: Greg Kroah-Hartman
Date: Sun Jun 09 2019 - 13:03:19 EST

From: Yifeng Li <tomli@xxxxxxxx>

commit 9dc20113988b9a75ea6b3abd68dc45e2d73ccdab upstream.

A fallthrough in switch/case was introduced in f627caf55b8e ("fbdev:
sm712fb: fix crashes and garbled display during DPMS modesetting"),
due to my copy-paste error, which would cause the memory clock frequency
for SM720 to be programmed to SM712.

Since it only reprograms the clock to a different frequency, it's only
a benign issue without visible side-effect, so it also evaded Sudip
Mukherjee's code review and regression tests. scripts/checkpatch.pl
also failed to discover the issue, possibly due to nested switch

This issue was found by Stephen Rothwell by building linux-next with

Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Fixes: f627caf55b8e ("fbdev: sm712fb: fix crashes and garbled display during DPMS modesetting")
Signed-off-by: Yifeng Li <tomli@xxxxxxxx>
Cc: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Cc: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/video/fbdev/sm712fb.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -898,6 +898,7 @@ static int smtc_blank(int blank_mode, st
case 0x712:
smtc_seqw(0x6a, 0x16);
smtc_seqw(0x6b, 0x02);
+ break;
case 0x720:
smtc_seqw(0x6a, 0x0d);
smtc_seqw(0x6b, 0x02);