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-rw-r--r--drivers/video/mbx/mbxfb.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/video/mbx/mbxfb.c b/drivers/video/mbx/mbxfb.c
index 6849ab75d40..cfc6bf3615b 100644
--- a/drivers/video/mbx/mbxfb.c
+++ b/drivers/video/mbx/mbxfb.c
@@ -118,8 +118,19 @@ static unsigned int mbxfb_get_pixclock(unsigned int pixclock_ps,
/* convert pixclock to KHz */
pixclock = PICOS2KHZ(pixclock_ps);
+ /* PLL output freq = (ref_clk * M) / (N * 2^P)
+ *
+ * M: 1 to 63
+ * N: 1 to 7
+ * P: 0 to 7
+ */
+
+ /* RAPH: When N==1, the resulting pixel clock appears to
+ * get divided by 2. Preventing N=1 by starting the following
+ * loop at 2 prevents this. Is this a bug with my chip
+ * revision or something I dont understand? */
for (m = 1; m < 64; m++) {
- for (n = 1; n < 8; n++) {
+ for (n = 2; n < 8; n++) {
for (p = 0; p < 8; p++) {
clk = (ref_clk * m) / (n * (1 << p));
err = (clk > pixclock) ? (clk - pixclock) :