From dd14f71cc62dd07b588cc6de935155e6fd3911c9 Mon Sep 17 00:00:00 2001 From: Krzysztof Helt Date: Tue, 31 Mar 2009 15:25:14 -0700 Subject: [PATCH] cirrusfb: fix clock doubling Cirrus' Alpine and Picasso4 chips uses DAC clock doubling to achieve full range of pixclock frequencies. [akpm@linux-foundation.org: fix spelling, use usual comment layout] Signed-off-by: Krzysztof Helt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/cirrusfb.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/video/cirrusfb.c b/drivers/video/cirrusfb.c index 65a1831ddd0d..15e2e6bfcbff 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); -- 2.20.1