From 4e64bcac453bd7225bbd597a07c2fcc4bd40e20e Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Thu, 12 Dec 2013 16:34:14 +0100 Subject: [PATCH] video: ipufb: Allow to disable fractional pixelclock divider The IPU has a fractional pixelclock divider. When used, this produces clock jitter which especially LVDS transceivers can't handle. Allow to disable it via platform_data. Signed-off-by: Sascha Hauer --- arch/arm/mach-imx/include/mach/imx-ipu-fb.h | 5 +++++ drivers/video/imx-ipu-fb.c | 11 +++++++++-- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/arm/mach-imx/include/mach/imx-ipu-fb.h b/arch/arm/mach-imx/include/mach/imx-ipu-fb.h index 43b3bda98..ee1a9b583 100644 --- a/arch/arm/mach-imx/include/mach/imx-ipu-fb.h +++ b/arch/arm/mach-imx/include/mach/imx-ipu-fb.h @@ -47,6 +47,11 @@ struct imx_ipu_fb_platform_data { void __iomem *framebuffer_ovl; /** hook to enable backlight and stuff */ void (*enable)(int enable); + /* + * Fractional pixelclock divider causes jitter which some displays + * or LVDS transceivers can't handle. Disable it if necessary. + */ + int disable_fractional_divider; }; #endif /* __MACH_IMX_IPU_FB_H__ */ diff --git a/drivers/video/imx-ipu-fb.c b/drivers/video/imx-ipu-fb.c index 8b4351580..2e65fdefa 100644 --- a/drivers/video/imx-ipu-fb.c +++ b/drivers/video/imx-ipu-fb.c @@ -43,6 +43,7 @@ struct ipu_fb_info { struct device_d *dev; unsigned int alpha; + int disable_fractional_divider; }; /* IPU DMA Controller channel definitions. */ @@ -409,7 +410,7 @@ static int sdc_init_panel(struct fb_info *info, enum disp_data_mapping fmt) struct fb_videomode *mode = info->mode; u32 reg, old_conf, div; enum ipu_panel panel = IPU_PANEL_TFT; - unsigned long pixel_clk; + unsigned long pixel_clk, rate; /* Init panel size and blanking periods */ reg = ((mode->hsync_len - 1) << 26) | @@ -466,7 +467,12 @@ static int sdc_init_panel(struct fb_info *info, enum disp_data_mapping fmt) * i.MX31 it (HSP_CLK) is <= 178MHz. Currently 128.267MHz */ pixel_clk = PICOS2KHZ(mode->pixclock) * 1000UL; - div = clk_get_rate(fbi->clk) * 16 / pixel_clk; + rate = clk_get_rate(fbi->clk); + + if (fbi->disable_fractional_divider) + div = DIV_ROUND_CLOSEST(rate, pixel_clk) * 16; + else + div = rate * 16 / pixel_clk; if (div < 0x40) { /* Divider less than 4 */ dev_dbg(&info->dev, @@ -1000,6 +1006,7 @@ static int imxfb_probe(struct device_d *dev) fbi->dev = dev; fbi->enable = pdata->enable; fbi->disp_data_fmt = pdata->disp_data_fmt; + fbi->disable_fractional_divider = pdata->disable_fractional_divider; info->priv = fbi; info->fbops = &imxfb_ops; info->num_modes = pdata->num_modes;