The patch titled
mbxfb: Fix a chip bug? resulting in wrong pixclock
has been added to the -mm tree. Its filename is
mbxfb-fix-a-chip-bug-resulting-in-wrong-pixclock.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: mbxfb: Fix a chip bug? resulting in wrong pixclock
From: Raphael Assenat <raph@xxxxxx>
This is a workaround for what I think is a bug in the 2700G chip.
The PLL output frequency is adustable using 3 values (M, N and P. See code
for formula). The N value range is documented to be 1 to 7 but when it is set
to 1, the output frequency is lower than it should be (divided by 2), giving
unexpected results such as no sync on a CRT display.
This patch prevents N=1 when searching for the best value for the requested
pixclock.
Signed-off-by: Raphael Assenat <raph@xxxxxx>
Signed-off-by: Antonino Daplas <adaplas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/video/mbx/mbxfb.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletion(-)
diff -puN drivers/video/mbx/mbxfb.c~mbxfb-fix-a-chip-bug-resulting-in-wrong-pixclock drivers/video/mbx/mbxfb.c
--- a/drivers/video/mbx/mbxfb.c~mbxfb-fix-a-chip-bug-resulting-in-wrong-pixclock
+++ a/drivers/video/mbx/mbxfb.c
@@ -118,8 +118,19 @@ static unsigned int mbxfb_get_pixclock(u
/* 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) :
_
Patches currently in -mm which might be from raph@xxxxxx are
mbxfb-fix-a-chip-bug-resulting-in-wrong-pixclock.patch
mbxfb-fix-framebuffer-size-smaller-than-requested.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
