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-rw-r--r--drivers/video/cirrusfb.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/drivers/video/cirrusfb.c b/drivers/video/cirrusfb.c
index 65a1831ddd0..15e2e6bfcbf 100644
--- a/drivers/video/cirrusfb.c
+++ b/drivers/video/cirrusfb.c
@@ -470,10 +470,25 @@ static int cirrusfb_check_pixclock(const struct fb_var_screeninfo *var,
/* If the frequency is greater than we can support, we might be able
* to use multiplexing for the video mode */
if (freq > maxclock) {
+ dev_err(info->device,
+ "Frequency greater than maxclock (%ld kHz)\n",
+ maxclock);
+ return -EINVAL;
+ }
+ /*
+ * Additional constraint: 8bpp uses DAC clock doubling to allow maximum
+ * pixel clock
+ */
+ if (var->bits_per_pixel == 8) {
switch (cinfo->btype) {
case BT_ALPINE:
+ case BT_PICASSO4:
+ if (freq > 85500)
+ cinfo->multiplexing = 1;
+ break;
case BT_GD5480:
- cinfo->multiplexing = 1;
+ if (freq > 135100)
+ cinfo->multiplexing = 1;
break;
default:
@@ -815,6 +830,8 @@ static int cirrusfb_set_par_foo(struct fb_info *info)
freq = PICOS2KHZ(var->pixclock);
if (cinfo->btype == BT_ALPINE && var->bits_per_pixel == 24)
freq *= 3;
+ if (cinfo->multiplexing)
+ freq /= 2;
bestclock(freq, &nom, &den, &div);